RFC 8431

A YANG Data Model for the Routing Information Base (RIB)

πŸ“… published September 2018, from ietf

Abstract πŸ¦‹

okay so the abstract is short and sweet: this doc defines a YANG data model for the Routing Information Base (RIB) that lines up with the Interface to the Routing System (I2RS) RIB information model. bestie, that's the whole pitch πŸ’…

Status of This Memo πŸ“œ

This is an Internet Standards Track document. 🌸

It's a product of the Internet Engineering Task Force (IETF), which means it has the consensus of the IETF community. It got public review and was approved for publication by the Internet Engineering Steering Group (IESG). If you want more on Internet Standards, check out Section 2 of RFC 7841 🫢

Info about the doc's current status, any errata, and how to send feedback lives at https://www.rfc-editor.org/info/rfc8431. Bookmark that one πŸ”–

Copyright (c) 2018 IETF Trust and the persons identified as the document authors. All rights reserved.

This document is subject to BCP 78 and the IETF Trust's Legal Provisions Relating to IETF Documents (https://trustee.ietf.org/license-info) in effect on the date of publication of this document. Please read these carefully, because they spell out your rights and restrictions for this document. Code Components pulled out of this document must include Simplified BSD License text as described in Section 4.e of the Trust Legal Provisions, and they come without warranty as described in the Simplified BSD License. legal stuff, but make it cute πŸŽ€

Table of Contents πŸ—ΊοΈ

1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   3
  1.1.  Requirements Language . . . . . . . . . . . . . . . . . .   3
  1.2.  Definitions and Abbreviations . . . . . . . . . . . . . .   3
  1.3.  Tree Diagrams . . . . . . . . . . . . . . . . . . . . . .   3
2.  Model Structure . . . . . . . . . . . . . . . . . . . . . . .   3
  2.1.  RIB Capability  . . . . . . . . . . . . . . . . . . . . .   8
  2.2.  Routing Instance and RIB  . . . . . . . . . . . . . . . .   8
  2.3.  Route . . . . . . . . . . . . . . . . . . . . . . . . . .   9
  2.4.  Nexthop . . . . . . . . . . . . . . . . . . . . . . . . .  11
  2.5.  RPC Operations  . . . . . . . . . . . . . . . . . . . . .  15
  2.6.  Notifications . . . . . . . . . . . . . . . . . . . . . .  20
3.  YANG Module . . . . . . . . . . . . . . . . . . . . . . . . .  22
4.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .  67
5.  Security Considerations . . . . . . . . . . . . . . . . . . .  67
6.  References  . . . . . . . . . . . . . . . . . . . . . . . . .  68
  6.1.  Normative References  . . . . . . . . . . . . . . . . . .  68
  6.2.  Informative References  . . . . . . . . . . . . . . . . .  69
Acknowledgements  . . . . . . . . . . . . . . . . . . . . . . . .  70
Contributors  . . . . . . . . . . . . . . . . . . . . . . . . . .  70
Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .  71

1. Introduction ✨

okay so the Interface to the Routing System (I2RS) [RFC7921] gives you read and write access to the info and state inside the routing process of routing elements. This happens through protocol message exchanges between I2RS clients and I2RS agents that sit on the routing system. One of I2RS's jobs is reading and writing data in the Routing Information Base (RIB) πŸ’– [I2RS-REQS] has a set of RIB use cases, and the RIB information model is defined in [RFC8430].

This document defines a YANG data model [RFC7950] [RFC6991] for the RIB. It covers the RIB use cases and lines up with the RIB information model. it's giving organized 🧚

1.1. Requirements Language

The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and "OPTIONAL" in this document are to be interpreted as described in BCP 14 [RFC2119] [RFC8174] when, and only when, they appear in all capitals, as shown here. the capitals are the whole vibe here, so only the all-caps versions count πŸ”₯

1.2. Definitions and Abbreviations πŸ“š

  • RIB: Routing Information Base
  • FIB: Forwarding Information Base
  • RPC: Remote Procedure Call
  • IM: Information Model. An abstract model of a conceptual domain, which is independent of a specific implementation or data representation.

1.3. Tree Diagrams 🌳

Tree diagrams in this document follow the notation defined in [RFC8340]. ✨

2. Model Structure ✨

Okay bestie, here's the big picture πŸ—ΊοΈ This figure shows an overview of the structure tree for the ietf-i2rs-rib module. To keep it readable, some details of the tree are left out, but don't worry, the subsections below cover the relevant bits πŸ’…

module: ietf-i2rs-rib
   +--rw routing-instance
      +--rw name              string
      +--rw interface-list* [name]
      |  +--rw name if:interface-ref
      +--rw router-id?        yang:dotted-quad
      +--rw lookup-limit?     uint8
      +--rw rib-list* [name]
         +--rw name              string
         +--rw address-family address-family-definition
         +--rw ip-rpf-check?     boolean
         +--rw route-list* [route-index]
         |  +--rw route-index                uint64
         |  +--rw match
         |  |  +--rw (route-type)?
         |  |     +--:(ipv4)
         |  |     |  ...
         |  |     +--:(ipv6)
         |  |     |  ...
         |  |     +--:(mpls-route)
         |  |     |  ...
         |  |     +--:(mac-route)
         |  |     |  ...
         |  |     +--:(interface-route)
         |  |        ...
         |  +--rw nexthop
         |  |  +--rw nexthop-id?           uint32
         |  |  +--rw sharing-flag?         boolean
         |  |  +--rw (nexthop-type)?
         |  |     +--:(nexthop-base)
         |  |     |  ...
         |  |     +--:(nexthop-chain) {nexthop-chain}?
         |  |     |  ...
         |  |     +--:(nexthop-replicate) {nexthop-replicate}?
         |  |     |  ...
         |  |     +--:(nexthop-protection) {nexthop-protection}?
         |  |     |  ...
         |  |     +--:(nexthop-load-balance) {nexthop-load-balance}?
         |  |        ...
         |  +--rw route-status
         |  |  ...
         |  +--rw route-attributes
         |  |  ...
         |  +--rw route-vendor-attributes
         +--rw nexthop-list* [nexthop-member-id]
            +--rw nexthop-member-id uint32

rpcs:
   +---x rib-add
   |  +---w input
   |  |  +---w name        string
   |  |  +---w address-family      address-family-definition
   |  |  +---w ip-rpf-check?   boolean
   |  +--ro output
   |     +--ro result boolean
   |     +--ro reason? string
   +---x rib-delete
   |  +---w input
   |  |  +---w name string
   |  +--ro output
   |     +--ro result boolean
   |     +--ro reason? string
   +---x route-add
   |  +---w input
   |  |  +---w return-failure-detail?   boolean
   |  |  +---w rib-name                 string
   |  |  +---w routes
   |  |     +---w route-list* [route-index]
   |  |        ...
   |  +--ro output
   |     +--ro success-count     uint32
   |     +--ro failed-count      uint32
   |     +--ro failure-detail
   |        +--ro failed-routes* [route-index]
   |           +--ro route-index uint32
   |           +--ro error-code? uint32
   +---x route-delete
   |  +---w input
   |  |  +---w return-failure-detail?   boolean
   |  |  +---w rib-name                 string
   |  |  +---w routes
   |  |     +---w route-list* [route-index]
   |  |        ...
   |  +--ro output
   |     +--ro success-count     uint32
   |     +--ro failed-count      uint32
   |     +--ro failure-detail
   |        +--ro failed-routes* [route-index]
   |           +--ro route-index uint32
   |           +--ro error-code? uint32
   +---x route-update
   |  +---w input
   |  |  +---w return-failure-detail?           boolean
   |  |  +---w rib-name                         string
   |  |  +---w (match-options)?
   |  |     +--:(match-route-prefix)
   |  |     |  ...
   |  |     +--:(match-route-attributes)
   |  |     |  ...
   |  |     +--:(match-route-vendor-attributes) {...}?
   |  |     |  ...
   |  |     +--:(match-nexthop)
   |  |        ...
   |  +--ro output
   |     +--ro success-count uint32
   |     +--ro failed-count uint32
   |     +--ro failure-detail
   |        +--ro failed-routes* [route-index]
   |           +--ro route-index uint32
   |           +--ro error-code? uint32
   +---x nh-add
   |  +---w input
   |  |  +---w rib-name              string
   |  |  +---w nexthop-id?           uint32
   |  |  +---w sharing-flag?         boolean
   |  |  +---w (nexthop-type)?
   |  |     +--:(nexthop-base)
   |  |     |  ...
   |  |     +--:(nexthop-chain) {nexthop-chain}?
   |  |     |  ...
   |  |     +--:(nexthop-replicate) {nexthop-replicate}?
   |  |     |  ...
   |  |     +--:(nexthop-protection) {nexthop-protection}?
   |  |     |  ...
   |  |     +--:(nexthop-load-balance) {nexthop-load-balance}?
   |  |        ...
   |  +--ro output
   |     +--ro result        boolean
   |     +--ro reason?       string
   |     +--ro nexthop-id?   uint32
   +---x nh-delete
      +---w input
      |  +---w rib-name              string
      |  +---w nexthop-id?           uint32
      |  +---w sharing-flag?         boolean
      |  +---w (nexthop-type)?
      |     +--:(nexthop-base)
      |     |  ...
      |     +--:(nexthop-chain) {nexthop-chain}?
      |     |  ...
      |     +--:(nexthop-replicate) {nexthop-replicate}?
      |     |  ...

      |     +--:(nexthop-protection) {nexthop-protection}?
      |     |  ...
      |     +--:(nexthop-load-balance) {nexthop-load-balance}?
      |        ...
      +--ro output
         +--ro result boolean
         +--ro reason? string
notifications:
   +---n nexthop-resolution-status-change
   |  +--ro nexthop
   |  |  +--ro nexthop-id?           uint32
   |  |  +--ro sharing-flag?         boolean
   |  |  +--ro (nexthop-type)?
   |  |     +--:(nexthop-base)
   |  |     |  ...
   |  |     +--:(nexthop-chain) {nexthop-chain}?
   |  |     |  ...
   |  |     +--:(nexthop-replicate) {nexthop-replicate}?
   |  |     |  ...
   |  |     +--:(nexthop-protection) {nexthop-protection}?
   |  |     |  ...
   |  |     +--:(nexthop-load-balance) {nexthop-load-balance}?
   |  |        ...
   |  +--ro nexthop-state nexthop-state-definition
   +---n route-change
      +--ro rib-name                 string
      +--ro address-family               address-family-definition
      +--ro route-index              uint64
      +--ro match
      |  +--ro (route-type)?
      |     +--:(ipv4)
      |     |  ...
      |     +--:(ipv6)
      |     |  ...
      |     +--:(mpls-route)
      |     |  ...
      |     +--:(mac-route)
      |     |  ...
      |     +--:(interface-route)
      |        ...
      +--ro route-installed-state route-installed-state-definition
      +--ro route-state         route-state-definition
      +--ro route-change-reasons* [route-change-reason]
         +--ro route-change-reason    route-change-reason-definition

Figure 1: Overview of I2RS RIB Module Structure πŸ¦‹

2.1. RIB Capability

RIB capability negotiation matters a LOT, because not every piece of hardware can support every kind of nexthop, and there might be a limit on how many levels of lookup can practically be performed πŸ” So a RIB data model needs a way for an external entity to learn about the functional capabilities of a network device πŸ’–

Nexthop chains are the other part of this. They let you specify multiple headers over a packet before that particular packet gets forwarded πŸŽ€ Not every network device can support every kind of nexthop chain, or an arbitrary number of headers chained together πŸ™ˆ That means the RIB data model needs a way to expose the nexthop chaining capability a given network device supports.

This module uses the feature and if-feature statements to get that capability advertisement done ✨

2.2. Routing Instance and RIB

A routing instance, in the RIB information model, is a collection of RIBs, interfaces, and routing protocol parameters 🌸 It creates a logical slice of the router, and it can let multiple different logical slices, across a set of routers, talk to each other 🫢 The routing protocol parameters control the information available in the RIBs. For more details, see Section 2.2 of [RFC8430] πŸ’œ

A routing instance can have multiple RIBs, so this model uses "list" to express them πŸ“ Here's the structure tree:

+--rw routing-instance
   +--rw name              string
   +--rw interface-list* [name]
   |  +--rw name if:interface-ref
   +--rw router-id?        yang:dotted-quad
   +--rw lookup-limit?     uint8
   +--rw rib-list* [name]
      +--rw name            string
      +--rw address-family      address-family-definition
      +--rw ip-rpf-check?   boolean
      +--rw route-list* [route-index]
         ... // refer to Section 2.3

Figure 2: Routing Instance Structure 🧚

2.3. Route

A route is essentially a match condition plus an action that follows that match 🎯 The match condition specifies the kind of route (e.g., IPv4, MPLS, Media Access Control (MAC), Interface, etc.) and the set of fields to match on πŸ’…

A route MUST contain the ROUTE_PREFERENCE attribute (see Section 2.3 of [RFC8430]) πŸ‘‘

On top of that, a route MUST associate with the following status attributes in responses to a RIB writing/reading operation πŸ“¬

  • Active: tells you whether a route has at least one fully resolved nexthop, which makes it eligible for installation in the FIB βœ…
  • Installed: tells you whether the route got installed in the FIB πŸ“¦
  • Reason: tells you the specific reason that caused the failure, e.g., "Not authorized" 🚫

And a route can also be associated with one or more optional route-attributes (e.g., route-vendor-attributes) 🌈

A RIB holds a bunch of routes, so the routes are expressed as a list under a specific RIB, and each RIB gets its own route list πŸ§ƒ

+--rw route-list* [route-index]
   +--rw route-index                uint64
   +--rw match
   |  +--rw (route-type)?
   |     +--:(ipv4)
   |     |  +--rw ipv4
   |     |     +--rw (ip-route-match-type)?
   |     |        +--:(dest-ipv4-address)
   |     |        |  ...
   |     |        +--:(src-ipv4-address)
   |     |        |  ...
   |     |        +--:(dest-src-ipv4-address)
   |     |           ...
   |     +--:(ipv6)
   |     |  +--rw ipv6
   |     |     +--rw (ip-route-match-type)?
   |     |        +--:(dest-ipv6-address)
   |     |        |  ...
   |     |        +--:(src-ipv6-address)
   |     |        |  ...
   |     |        +--:(dest-src-ipv6-address)
   |     |           ...
   |     +--:(mpls-route)
   |     |  +--rw mpls-label              uint32
   |     +--:(mac-route)
   |     |  +--rw mac-address             uint32
   |     +--:(interface-route)
   |        +--rw interface-identifier if:interface-ref
   +--rw nexthop
   |  ...(refer to Section 2.4)

Figure 3: Routes Structure πŸ’–

2.4. Nexthop ✨

okay bestie, let's talk nexthops πŸ’… A nexthop is basically the thing you get back once a route lookup is done πŸ¦‹ As shown in Figure 4 of [RFC8430], it's built to handle stuff like load-balancing, protection, multicast, or any combo of those, so it's modeled as a multilevel structure that supports recursion 🌈 The first level has the following four types:

  • Base: The "base" nexthop is the foundation of all other nexthop types πŸŽ€ It includes these basic nexthops:
    • nexthop-id
    • IPv4 address
    • IPv6 address
    • egress-interface
    • egress-interface with IPv4 address
    • egress-interface with IPv6 address
    • egress-interface with MAC address
    • logical-tunnel
    • tunnel-encapsulation
    • tunnel-decapsulation
    • rib-name
  • Chain: The "chain" nexthop gives you a way to perform multiple operations on a packet by logically combining them πŸ”—
  • Load-Balance: The "load-balance" nexthop is made for a load-balance case, where it normally has multiple weighted nexthops βš–οΈ
  • Protection: The "protection" nexthop is made for a protection scenario, where it normally has a primary nexthop and a standby nexthop πŸ›‘οΈ
  • Replicate: The "replicate" nexthop is made for forwarding to multiple destinations πŸ“£

The structure tree of nexthop is shown in the following figures πŸ‘‘

+--rw nexthop
|  +--rw nexthop-id?           uint32
|  +--rw sharing-flag?         boolean
|  +--rw (nexthop-type)?
|     +--:(nexthop-base)
|     |  ...(refer to Figure 5)
|     +--:(nexthop-chain) {nexthop-chain}?
|     |  +--rw nexthop-chain
|     |     +--rw nexthop-list* [nexthop-member-id]
|     |        +--rw nexthop-member-id uint32
|     +--:(nexthop-replicate) {nexthop-replicate}?
|     |  +--rw nexthop-replicate
|     |     +--rw nexthop-list* [nexthop-member-id]
|     |        +--rw nexthop-member-id uint32
|     +--:(nexthop-protection) {nexthop-protection}?
|     |  +--rw nexthop-protection
|     |     +--rw nexthop-list* [nexthop-member-id]
|     |        +--rw nexthop-member-id uint32
|     |        +--rw nexthop-preference nexthop-preference-definition
|     +--:(nexthop-load-balance) {nexthop-load-balance}?
|        +--rw nexthop-lb
|           +--rw nexthop-list* [nexthop-member-id]
|              +--rw nexthop-member-id uint32
|              +--rw nexthop-lb-weight nexthop-lb-weight-definition

Figure 4: Nexthop Structure

Figure 5 (as shown below) is a subtree of nexthop 🌸 It's under the nexthop base node and shows the structure of the "base" nexthop, so this is the one with all the good stuff 🧚

+--:(nexthop-base)
|  +--rw nexthop-base
|     +--rw (nexthop-base-type)?
|        +--:(special-nexthop)
|        |  +--rw special? special-nexthop-definition
|        +--:(egress-interface-nexthop)
|        |  +--rw outgoing-interface if:interface-ref
|        +--:(ipv4-address-nexthop)
|        |  +--rw ipv4-address inet:ipv4-address
|        +--:(ipv6-address-nexthop)
|        |  +--rw ipv6-address inet:ipv6-address
|        +--:(egress-interface-ipv4-nexthop)
|        |  +--rw egress-interface-ipv4-address
|        |     +--rw outgoing-interface if:interface-ref
|        |     +--rw ipv4-address       inet:ipv4-address
|        +--:(egress-interface-ipv6-nexthop)
|        |  +--rw egress-interface-ipv6-address
|        |     +--rw outgoing-interface if:interface-ref
|        |     +--rw ipv6-address       inet:ipv6-address
|        +--:(egress-interface-mac-nexthop)
|        |  +--rw egress-interface-mac-address
|        |     +--rw outgoing-interface if:interface-ref
|        |     +--rw ieee-mac-address yang:mac-address
|        +--:(tunnel-encapsulation-nexthop) {nexthop-tunnel}?
|        |  +--rw tunnel-encapsulation
|        |     +--rw (tunnel-type)?
|        |        +--:(ipv4) {ipv4-tunnel}?
|        |        |  +--rw ipv4-header
|        |        |     +--rw src-ipv4-address inet:ipv4-address
|        |        |     +--rw dest-ipv4-address inet:ipv4-address
|        |        |     +--rw protocol          uint8
|        |        |     +--rw ttl?              uint8
|        |        |     +--rw dscp?             uint8
|        |        +--:(ipv6) {ipv6-tunnel}?
|        |        |  +--rw ipv6-header
|        |        |     +--rw src-ipv6-address inet:ipv6-address
|        |        |     +--rw dest-ipv6-address inet:ipv6-address
|        |        |     +--rw next-header       uint8
|        |        |     +--rw traffic-class? uint8
|        |        |     +--rw flow-label?
|        |        |             inet:ipv6-flow-label
|        |        |     +--rw hop-limit?        uint8
|        |        +--:(mpls) {mpls-tunnel}?
|        |        |  +--rw mpls-header
|        |        |     +--rw label-operations* [label-oper-id]
|        |        |        +--rw label-oper-id uint32
|        |        |        +--rw (label-actions)?
|        |        |           +--:(label-push)
|        |        |           |  +--rw label-push
|        |        |           |     +--rw label        uint32
|        |        |           |     +--rw s-bit?       boolean
|        |        |           |     +--rw tc-value? uint8
|        |        |           |     +--rw ttl-value? uint8
|        |        |           +--:(label-swap)
|        |        |              +--rw label-swap
|        |        |                 +--rw out-label     uint32
|        |        |                 +--rw ttl-action?
|        |        |                         ttl-action-definition
|        |        +--:(gre) {gre-tunnel}?
|        |        |  +--rw gre-header
|        |        |     +--rw (dest-address-type)?
|        |        |     |  +--:(ipv4)
|        |        |     |  |  +--rw ipv4-dest inet:ipv4-address
|        |        |     |  +--:(ipv6)
|        |        |     |     +--rw ipv6-dest inet:ipv6-address
|        |        |     +--rw protocol-type uint16
|        |        |     +--rw key?          uint64
|        |        +--:(nvgre) {nvgre-tunnel}?
|        |        |  +--rw nvgre-header
|        |        |     +--rw (nvgre-type)?
|        |        |     |  +--:(ipv4)
|        |        |     |  |  +--rw src-ipv4-address inet:ipv4-address
|        |        |     |  |  +--rw dest-ipv4-address inet:ipv4-address
|        |        |     |  |  +--rw protocol          uint8
|        |        |     |  |  +--rw ttl?              uint8
|        |        |     |  |  +--rw dscp?             uint8
|        |        |     |  +--:(ipv6)
|        |        |     |     +--rw src-ipv6-address inet:ipv6-address
|        |        |     |     +--rw dest-ipv6-address inet:ipv6-address
|        |        |     |     +--rw next-header       uint8
|        |        |     |     +--rw traffic-class?    uint8
|        |        |     |     +--rw flow-label?
|        |        |     |             inet:ipv6-flow-label
|        |        |     |     +--rw hop-limit?        uint8
|        |        |     +--rw virtual-subnet-id uint32
|        |        |     +--rw flow-id?          uint8
|        |        +--:(vxlan) {vxlan-tunnel}?
|        |           +--rw vxlan-header
|        |              +--rw (vxlan-type)?
|        |              |  +--:(ipv4)
|        |              |  |  +--rw src-ipv4-address inet:ipv4-address
|        |              |  |  +--rw dest-ipv4-address inet:ipv4-address
|        |              |  |  +--rw protocol             uint8
|        |              |  |  +--rw ttl?                 uint8
|        |              |  |  +--rw dscp?                uint8
|        |              |  +--:(ipv6)
|        |              |     +--rw src-ipv6-address inet:ipv6-address
|        |              |     +--rw dest-ipv6-address inet:ipv6-address
|        |              |     +--rw next-header          uint8
|        |              |     +--rw traffic-class?       uint8
|        |              |     +--rw flow-label? inet:ipv6-flow-label
|        |              |     +--rw hop-limit?           uint8
|        |              +--rw vxlan-identifier     uint32
|        +--:(tunnel-decapsulation-nexthop) {nexthop-tunnel}?
|        |  +--rw tunnel-decapsulation
|        |     +--rw (tunnel-type)?
|        |        +--:(ipv4) {ipv4-tunnel}?
|        |        |  +--rw ipv4-decapsulation
|        |        |     +--rw ipv4-decapsulation
|        |        |             tunnel-decapsulation-action-definition
|        |        |     +--rw ttl-action?   ttl-action-definition
|        |        +--:(ipv6) {ipv6-tunnel}?
|        |        |  +--rw ipv6-decapsulation
|        |        |     +--rw ipv6-decapsulation
|        |        |             tunnel-decapsulation-action-definition
|        |        |     +--rw hop-limit-action?
|        |        |             hop-limit-action-definition
|        |        +--:(mpls) {mpls-tunnel}?
|        |           +--rw label-pop
|        |              +--rw label-pop     mpls-label-action-definition
|        |              +--rw ttl-action?   ttl-action-definition
|        +--:(logical-tunnel-nexthop) {nexthop-tunnel}?
|        |  +--rw logical-tunnel
|        |     +--rw tunnel-type tunnel-type-definition
|        |     +--rw tunnel-name string
|        +--:(rib-name-nexthop)
|        |  +--rw rib-name?                        string
|        +--:(nexthop-identifier)
|           +--rw nexthop-ref                      nexthop-ref

Figure 5: Nexthop Base Structure

That's the whole nexthop picture, bestie 🫢 Keep it in mind as we keep going πŸ’œ

2.5. RPC Operations πŸ’…

Okay bestie, so this module defines the following RPC operations 🌸:

  • rib-add: Add a RIB to a routing instance πŸŽ€. The inputs are the name of the RIB, the address family of the RIB, and (optionally) whether the RPF check is enabled. The output is the result of the add operation:
    • true - success
    • false - failed (when failed, the I2RS agent may return the specific reason that caused the failure)
  • rib-delete: Delete a RIB from a routing instance πŸ—‘οΈ. When a RIB gets deleted, all the routes installed in it get deleted too, so be careful 😭. A rib-name is passed as the input. The output is the result of the delete operation:
    • true - success
    • false - failed (when failed, the I2RS agent may return the specific reason that caused the failure)
  • route-add: Add a route or a set of routes to a RIB πŸ¦‹. The inputs are the name of the RIB, the route prefix(es), the route-attributes, the route-vendor-attributes, the nexthop, and the "whether to return failure details" indication. Before calling the route-add rpc, it is required to call the nh-add rpc to create and/or return the nexthop identifier. However, in situations when the nexthop already exists and the nexthop-id is known, this action is not expected. The output is a combination of the route operation states while querying the appropriate node in the data tree, which includes:
    • success-count: the number of routes that were successfully added;
    • failed-count: the number of the routes that failed to be added; and,
    • failure-detail: this shows the specific routes that failed to be added.
  • route-delete: Delete a route or a set of routes from a RIB 🧹. The inputs are the name of the RIB, the route prefix(es), and the "whether to return failure details" indication. The output is a combination of route operation states, which includes:
    • success-count: the number of routes that were successfully deleted;
    • failed-count: the number of the routes that failed to be deleted; and,
    • failure-detail: this shows the specific routes that failed to be deleted.
  • route-update: Update a route or a set of routes ✨. The inputs are the name of the RIB, the route prefix(es), the route-attributes, the route-vendor-attributes, or the nexthop. The match conditions can be either route prefix(es), route-attributes, route-vendor-attributes, or nexthops. The update actions include the following: update the nexthops, update the route-attributes, and update the route-vendor-attributes. The output is a combination of the route operation states, which includes:
    • success-count: the number of routes that were successfully updated;
    • failed-count: the number of the routes that failed to be updated; and,
    • failure-detail: this shows the specific routes that failed to be updated.
  • nh-add: Add a nexthop to a RIB πŸ“. The inputs are the name of the RIB and the nexthop. The network node is required to allocate a nexthop identifier to the nexthop. The outputs include the result of the nexthop add operation.
    • true - success (when success, a nexthop identifier will be returned to the I2RS client)
    • false - failed (when failed, the I2RS agent may return the specific reason that caused the failure)
  • nh-delete: Delete a nexthop from a RIB πŸ‘‹. The inputs are the name of the RIB and a nexthop or nexthop identifier. The output is the result of the delete operation:
    • true - success
    • false - failed (when failed, the I2RS agent may return the specific reason that caused the failure)

Here's the structure tree of the rpcs, no cap, it's very clean 🧚:

   rpcs:
      +---x rib-add
      |  +---w input
      |  |  +---w rib-name        string
      |  |  +---w address-family      address-family-definition
      |  |  +---w ip-rpf-check?   boolean
      |  +--ro output
      |     +--ro result uint32
      |     +--ro reason? string
      +---x rib-delete
      |  +---w input
      |  |  +---w rib-name string
      |  +--ro output
      |     +--ro result uint32
      |     +--ro reason? string
      +---x route-add
      |  +---w input
      |  |  +---w return-failure-detail?   boolean
      |  |  +---w rib-name                 string
      |  |  +---w routes
      |  |     +---w route-list* [route-index]
      |  |        ...
      |  +--ro output
      |     +--ro success-count     uint32
      |     +--ro failed-count      uint32
      |     +--ro failure-detail
      |        +--ro failed-routes* [route-index]
      |           +--ro route-index uint32
      |           +--ro error-code? uint32
      +---x route-delete
      |  +---w input
      |  |  +---w return-failure-detail?   boolean
      |  |  +---w rib-name                 string
      |  |  +---w routes
      |  |     +---w route-list* [route-index]
      |  |        ...
      |  +--ro output
      |     +--ro success-count     uint32
      |     +--ro failed-count      uint32
      |     +--ro failure-detail
      |        +--ro failed-routes* [route-index]
      |           +--ro route-index uint32
      |           +--ro error-code? uint32
      +---x route-update
      |  +---w input
      |  |  +---w return-failure-detail?           boolean
      |  |  +---w rib-name                         string
      |  |  +---w (match-options)?
      |  |     +--:(match-route-prefix)
      |  |     |  ...
      |  |     +--:(match-route-attributes)
      |  |     |  ...
      |  |     +--:(match-route-vendor-attributes) {...}?
      |  |     |  ...
      |  |     +--:(match-nexthop)
      |  |        ...
      |  +--ro output
      |     +--ro success-count uint32
      |     +--ro failed-count uint32
      |     +--ro failure-detail
      |        +--ro failed-routes* [route-index]
      |           +--ro route-index uint32
      |           +--ro error-code? uint32
      +---x nh-add
      |  +---w input
      |  |  +---w rib-name              string
      |  |  +---w nexthop-id?           uint32
      |  |  +---w sharing-flag?         boolean
      |  |  +---w (nexthop-type)?
      |  |     ...
      |  +--ro output
      |     +--ro result        uint32
      |     +--ro reason?       string
      |     +--ro nexthop-id?   uint32
      +---x nh-delete
         +---w input
         |  +---w rib-name              string
         |  +---w nexthop-id?           uint32
         |  +---w sharing-flag?         boolean
         |  +---w (nexthop-type)?
         |     ...
         +--ro output
            +--ro result uint32
            +--ro reason? string

Figure 6: RPCs Structure 🌈

2.6. Notifications πŸ””

Asynchronous notifications are sent by the RIB manager of a network device to an external entity when some event triggers on the network device. An implementation of this RIB data model MUST support sending two kinds of asynchronous notifications πŸ’œ.

  1. Route change notification:
    • Installed (indicates whether the route got installed in the FIB)
    • Active (indicates whether a route has at least one fully resolved nexthop and is therefore eligible for installation in the FIB)
    • Reason (e.g., "Not authorized")
  2. Nexthop resolution status notification

Nexthops can be fully resolved or unresolved 🧩.

A resolved nexthop has an adequate level of information to send the outgoing packet towards the destination by forwarding it on an interface to a directly connected neighbor.

An unresolved nexthop is something that requires the RIB manager to determine the final resolved nexthop. In one example, a nexthop could be an IP address. The RIB manager would resolve how to reach that IP address, e.g., by checking if that particular IP address is reachable by regular IP forwarding, by an MPLS tunnel, or by both. If the RIB manager cannot resolve the nexthop, then the nexthop remains in an unresolved state and is not a suitable candidate for installation in the FIB πŸ™ˆ.

An implementation of this RIB data model MUST support sending route-change notifications whenever a route transitions between the following states:

  • from the active state to the inactive state
  • from the inactive state to the active state
  • from the installed state to the uninstalled state
  • from the uninstalled state to the installed state

A single notification MAY be used when a route transitions from inactive/uninstalled to active/installed or in the other direction.

The structure tree of the notifications looks like this, iykyk πŸ¦‹:

   notifications:
        +---n nexthop-resolution-status-change
        |  +--ro nexthop
        |  |  +--ro nexthop-id            uint32
        |  |  +--ro sharing-flag          boolean
        |  |  +--ro (nexthop-type)?
        |  |     +--:(nexthop-base)
        |  |     |  ...
        |  |     +--:(nexthop-chain) {nexthop-chain}?
        |  |     |  ...
        |  |     +--:(nexthop-replicate) {nexthop-replicate}?
        |  |     |  ...
        |  |     +--:(nexthop-protection) {nexthop-protection}?
        |  |     |  ...
        |  |     +--:(nexthop-load-balance) {nexthop-load-balance}?
        |  |        ...
        |  +--ro nexthop-state nexthop-state-definition
        +---n route-change
           +--ro rib-name                 string
           +--ro address-family           address-family-definition
           +--ro route-index              uint64
           +--ro match
           |  +--ro (route-type)?
           |     +--:(ipv4)
           |     |  ...
           |     +--:(ipv6)
           |     |  ...
           |     +--:(mpls-route)
           |     |  ...
           |     +--:(mac-route)
           |     |  ...
           |     +--:(interface-route)
           |        ...
           +--ro route-installed-state route-installed-state-definition
           +--ro route-state              route-state-definition
           +--ro route-change-reason      route-change-reason-definition

Figure 7: Notifications Structure 🌸


3. YANG Module 🧁

This YANG module references [RFC2784], [RFC7348], [RFC7637], and [RFC8344] πŸŽ€.

   <CODE BEGINS> file "ietf-i2rs-rib@2018-09-13.yang"

   module ietf-i2rs-rib {
     yang-version 1.1;
     namespace "urn:ietf:params:xml:ns:yang:ietf-i2rs-rib";
     prefix iir;

     import ietf-inet-types {
       prefix inet;
       reference "RFC 6991";
     }
     import ietf-interfaces {
       prefix if;
       reference "RFC 8344";
     }
     import ietf-yang-types {
       prefix yang;
       reference "RFC 6991";
     }

     organization
       "IETF I2RS (Interface to Routing System) Working Group";
     contact
       "WG Web:   <https://datatracker.ietf.org/wg/i2rs/>
        WG List:  <mailto:i2rs@ietf.org>

        Editor:   Lixing Wang
                  <mailto:wang_little_star@sina.com>

        Editor:   Mach(Guoyi) Chen
                  <mailto:mach.chen@huawei.com>

        Editor:   Amit Dass
                  <mailto:dass.amit@gmail.com>

        Editor:   Hariharan Ananthakrishnan
                  <mailto:hari@netflix.com>

        Editor:   Sriganesh Kini
                  <mailto:sriganeshkini@gmail.com>

        Editor:   Nitin Bahadur
                  <mailto:nitin_bahadur@yahoo.com>";

okay bestie, the module header is basically the sign-in page 🫢 Here's the rest of the YANG module, and the features are literally on/off switches for what a node can do ✨

     description
       "This module defines a YANG data model for
        Routing Information Base (RIB) that aligns
        with the I2RS RIB information model.

        Copyright (c) 2018 IETF Trust and the persons
        identified as authors of the code.  All rights reserved.

        Redistribution and use in source and binary forms, with or
        without modification, is permitted pursuant to, and subject
        to the license terms contained in, the Simplified BSD License
        set forth in Section 4.c of the IETF Trust's Legal Provisions
        Relating to IETF Documents
        (http://trustee.ietf.org/license-info).

        This version of this YANG module is part of RFC 8341; see
        the RFC itself for full legal notices.";

     revision 2018-09-13 {
       description
         "initial revision";
       reference "RFC 8431";
     }

     //Features

     feature nexthop-tunnel {
       description
         "This feature means that a node supports
          tunnel nexthop capability.";
     }

     feature nexthop-chain {
       description
         "This feature means that a node supports
          chain nexthop capability.";
     }

     feature nexthop-protection {
       description
         "This feature means that a node supports
          protection nexthop capability.";
     }

     feature nexthop-replicate {
       description
         "This feature means that a node supports
          replicate nexthop capability.";

     }

     feature nexthop-load-balance {
       description
         "This feature means that a node supports
          load-balance nexthop capability.";
     }

     feature ipv4-tunnel {
       description
         "This feature means that a node supports
          IPv4 tunnel encapsulation capability.";
     }

     feature ipv6-tunnel {
       description
         "This feature means that a node supports
          IPv6 tunnel encapsulation capability.";
     }

     feature mpls-tunnel {
       description
         "This feature means that a node supports
          MPLS tunnel encapsulation capability.";
     }

     feature vxlan-tunnel {
       description
         "This feature means that a node supports
          Virtual eXtensible Local Area Network
          (VXLAN) tunnel encapsulation capability.";
       reference "RFC 7348";
     }

     feature gre-tunnel {
       description
         "This feature means that a node supports
          GRE tunnel encapsulation capability.";
       reference "RFC 2784";
     }

     feature nvgre-tunnel {
       description
         "This feature means that a node supports
          Network Virtualization Using GRE (NVGRE)
          tunnel encapsulation capability.";
       reference "RFC 7637";
     }
     feature route-vendor-attributes {
       description
         "This feature means that a node supports
          route vendor attributes.";
     }

     //Identities and Type Definitions

     identity mpls-label-action {
       description
         "Base identity from which all MPLS label
          operations are derived.

          The MPLS label stack operations include:
          push - to add a new label to a label stack
          pop -  to pop the top label from a label stack
          swap - to exchange the top label of a label
                 stack with a new label";
     }

     identity label-push {
       base mpls-label-action;
       description
         "MPLS label stack operation: push.";
     }

     identity label-pop {
       base mpls-label-action;
       description
         "MPLS label stack operation: pop.";
     }

     identity label-swap {
       base mpls-label-action;
       description
         "MPLS label stack operation: swap.";
     }

     typedef mpls-label-action-definition {
       type identityref {
         base mpls-label-action;
       }
       description
         "MPLS label action definition.";
     }

     identity tunnel-decapsulation-action {
       description

         "Base identity from which all tunnel decapsulation
          actions are derived.
          Tunnel decapsulation actions include
          ipv4-decapsulation (to decapsulate an IPv4 tunnel)
          ipv6-decapsulation (to decapsulate an IPv6 tunnel)";
     }

     identity ipv4-decapsulation {
       base tunnel-decapsulation-action;
       description
         "IPv4 tunnel decapsulation.";
     }

     identity ipv6-decapsulation {
       base tunnel-decapsulation-action;
       description
         "IPv6 tunnel decapsulation.";
     }

     typedef tunnel-decapsulation-action-definition {
       type identityref {
         base tunnel-decapsulation-action;
       }
       description
         "Tunnel decapsulation definition.";
     }

     identity ttl-action {
       description
         "Base identity from which all TTL
          actions are derived.";
     }

     identity no-action {
       base ttl-action;
       description
         "Do nothing regarding the TTL.";
     }

     identity copy-to-inner {
       base ttl-action;
       description
         "Copy the TTL of the outer header
          to the inner header.";
     }

     identity decrease-and-copy-to-inner {
       base ttl-action;
       description
         "Decrease TTL by one and copy the TTL
          to the inner header.";
     }

     identity decrease-and-copy-to-next {
       base ttl-action;
       description
         "Decrease TTL by one and copy the TTL
          to the next header; for example, when
          MPLS label swapping, decrease the TTL
          of the in_label and copy it to the
          out_label.";
     }

     typedef ttl-action-definition {
       type identityref {
         base ttl-action;
       }
       description
         "TTL action definition.";
     }

     identity hop-limit-action {
       description
         "Base identity from which all hop limit
          actions are derived.";
     }

     identity hop-limit-no-action {
       base hop-limit-action;
       description
         "Do nothing regarding the hop limit.";
     }

     identity hop-limit-copy-to-inner {
       base hop-limit-action;
       description
         "Copy the hop limit of the outer header
          to the inner header.";
     }

     typedef hop-limit-action-definition {
       type identityref {
         base hop-limit-action;
       }
       description
         "IPv6 hop limit action definition.";

     }

     identity special-nexthop {
       description
         "Base identity from which all special
          nexthops are derived.";
     }

     identity discard {
       base special-nexthop;
       description
         "This indicates that the network
          device should drop the packet and
          increment a drop counter.";
     }

     identity discard-with-error {
       base special-nexthop;
       description
         "This indicates that the network
          device should drop the packet,
          increment a drop counter, and send
          back an appropriate error message
          (like ICMP error).";
     }

     identity receive {
       base special-nexthop;
       description
         "This indicates that the traffic is
          destined for the network device, e.g.,
          protocol packets or Operations,
          Administration, and Maintenance (OAM) packets.
          All locally destined traffic SHOULD be
          throttled to avoid a denial-of-service
          attack on the router's control plane.  An
          optional rate-limiter can be specified
          to indicate how to throttle traffic
          destined for the control plane.";
     }

     identity cos-value {
       base special-nexthop;
       description
         "Cos-value special nexthop.";
     }

     typedef special-nexthop-definition {

       type identityref {
         base special-nexthop;
       }
       description
         "Special nexthop definition.";
     }

     identity ip-route-match-type {
       description
         "Base identity from which all route
          match types are derived.
          The route match type could be:
          match source, or
          match destination, or
          match source and destination.";
     }

     identity match-ip-src {
       base ip-route-match-type;
       description
         "Source route match type.";
     }

     identity match-ip-dest {
       base ip-route-match-type;
       description
         "Destination route match type";
     }

     identity match-ip-src-dest {
       base ip-route-match-type;
       description
         "Source and Destination route match type";
     }

     typedef ip-route-match-type-definition {
       type identityref {
         base ip-route-match-type;
       }
       description
         "IP route match type definition.";
     }

     identity address-family {
       description
         "Base identity from which all RIB
          address families are derived.";
     }
     identity ipv4-address-family {
       base address-family;
       description
         "IPv4 RIB address family.";
     }

     identity ipv6-address-family {
       base address-family;
       description
         "IPv6 RIB address family.";
     }

     identity mpls-address-family {
       base address-family;
       description
         "MPLS RIB address family.";
     }

     identity ieee-mac-address-family {
       base address-family;
       description
         "MAC RIB address family.";
     }

     typedef address-family-definition {
       type identityref {
         base address-family;
       }
       description
         "RIB address family definition.";
     }

     identity route-type {
       description
         "Base identity from which all route types
          are derived.";
     }

     identity ipv4-route {
       base route-type;
       description
         "IPv4 route type.";
     }

     identity ipv6-route {
       base route-type;
       description
         "IPv6 route type.";

     }

     identity mpls-route {
       base route-type;
       description
         "MPLS route type.";
     }

     identity ieee-mac {
       base route-type;
       description
         "MAC route type.";
     }

     identity interface {
       base route-type;
       description
         "Interface route type.";
     }

     typedef route-type-definition {
       type identityref {
         base route-type;
       }
       description
         "Route type definition.";
     }

     identity tunnel-type {
       description
         "Base identity from which all tunnel
          types are derived.";
     }

     identity ipv4-tunnel {
       base tunnel-type;
       description
         "IPv4 tunnel type";
     }

     identity ipv6-tunnel {
       base tunnel-type;
       description
         "IPv6 tunnel type";
     }

     identity mpls-tunnel {
       base tunnel-type;
       description
         "MPLS tunnel type";
     }

     identity gre-tunnel {
       base tunnel-type;
       description
         "GRE tunnel type";
     }

     identity vxlan-tunnel {
       base tunnel-type;
       description
         "VXLAN tunnel type";
     }

     identity nvgre-tunnel {
       base tunnel-type;
       description
         "NVGRE tunnel type";
     }

     typedef tunnel-type-definition {
       type identityref {
         base tunnel-type;
       }
       description
         "Tunnel type definition.";
     }

     identity route-state {
       description
         "Base identity from which all route
          states are derived.";
     }

     identity active {
       base route-state;
       description
         "Active state.";
     }

     identity inactive {
       base route-state;
       description
         "Inactive state.";
     }
     typedef route-state-definition {
       type identityref {
         base route-state;
       }
       description
         "Route state definition.";
     }

the special-nexthop bit is the spiciest part 🌢️ the receive identity literally says traffic SHOULD be throttled so nobody DoS's the router's control plane πŸ’€ that's the vibe! πŸ”₯

Okay bestie, the YANG module keeps going, and this part is where the states and reasons get their identities. πŸ¦‹ Routes and nexthops can be in different states, and every change comes with a reason, so the model needs named values for all of it. ✨

Let's start with the nexthop states. πŸ’–

identity nexthop-state {
  description
    "Base identity from which all nexthop
     states are derived.";
}

identity resolved {
  base nexthop-state;
  description
    "Resolved nexthop state.";
}

identity unresolved {
  base nexthop-state;
  description
    "Unresolved nexthop state.";
}

typedef nexthop-state-definition {
  type identityref {
    base nexthop-state;
  }
  description
    "Nexthop state definition.";
}

identity route-installed-state {
  description
    "Base identity from which all route
     installed states are derived.";
}

identity uninstalled {
  base route-installed-state;
  description
    "Uninstalled state.";
}

identity installed {
  base route-installed-state;
  description
    "Installed state.";
}

typedef route-installed-state-definition {
  type identityref {
    base route-installed-state;
  }
  description
    "Route installed state definition.";
}

Next up are the route change reasons, which explain why a route changed. This is the part that makes debugging way less of a mystery. πŸ”βœ¨

//Route Change Reason Identities

identity route-change-reason {
  description
    "Base identity from which all route change
     reasons are derived.";
}

identity lower-route-preference {
  base route-change-reason;
  description
    "This route was installed in the FIB because it had
     a lower route preference value (and thus was more
     preferred) than the route it replaced.";
}

identity higher-route-preference {
  base route-change-reason;
  description
    "This route was uninstalled from the FIB because it had
     a higher route preference value (and thus was less
     preferred) than the route that replaced it.";
}

identity resolved-nexthop {
  base route-change-reason;
  description
    "This route was made active because at least
     one of its nexthops was resolved.";
}

identity unresolved-nexthop {
  base route-change-reason;
  description
    "This route was made inactive because all of
     its nexthops are unresolved.";

}

typedef route-change-reason-definition {
  type identityref {
    base route-change-reason;
  }
  description
    "Route change reason definition.";
}

Now the two nexthop typedefs that control protection and load balancing. The preference one picks the winners for protection schemes (lowest number wins πŸ†), and the weight one splits traffic πŸ’…. 🌈

typedef nexthop-preference-definition {
  type uint8 {
    range "1..99";
  }
  description
    "Nexthop-preference is used for protection schemes.
     It is an integer value between 1 and 99.  Lower
     values are preferred.  To download N
     nexthops to the FIB, the N nexthops with the lowest
     value are selected.  If there are more than N
     nexthops that have the same preference, an
     implementation of the I2RS client should select N
     nexthops and download them.  As for how to select
     the nexthops, this is left to the implementations.";
}

typedef nexthop-lb-weight-definition {
  type uint8 {
    range "1..99";
  }
  description
    "Nexthop-lb-weight is used for load-balancing.
     Each list member SHOULD be assigned a weight
     between 1 and 99.  The weight determines the
     proportion of traffic to be sent over a nexthop
     used for forwarding as a ratio of the weight of
     this nexthop divided by the sum of the weights
     of all the nexthops of this route that are used
     for forwarding.  To perform equal load-balancing,
     one MAY specify a weight of 0 for all the member
     nexthops.  The value 0 is reserved for equal
     load-balancing and, if applied, MUST be applied
     to all member nexthops.
     Note that the weight of 0 is special because of
     historical reasons.  It's typically used in
     hardware devices to signify ECMP.";
}
typedef nexthop-ref {
  type leafref {
    path  "/iir:routing-instance" +
          "/iir:rib-list" +
          "/iir:route-list" +
          "/iir:nexthop" +
          "/iir:nexthop-id";
  }
  description
    "A nexthop reference that provides
     an indirection reference to a nexthop.";
}

Last up in this part are the groupings, which are the reusable building blocks for prefixes, routes, and nexthop lists. Think of them as the outfit pieces that get mixed and matched all over the module. πŸ‘—πŸŽ€

//Groupings

grouping route-prefix {
  description
    "The common attributes used for all types of route prefixes.";
  leaf route-index {
    type uint64;
    mandatory true;
    description
      "Route index.";
  }
  container match {
    description
      "The match condition specifies the
       kind of route (IPv4, MPLS, etc.)
       and the set of fields to match on.";
    choice route-type {
      description
        "Route types: IPv4, IPv6, MPLS, MAC, etc.";
      case ipv4 {
        description
          "IPv4 route case.";
        container ipv4 {
          description
            "IPv4 route match.";
          choice ip-route-match-type {
            description
              "IP route match type options:
               match source, or
               match destination, or
               match source and destination.";
            case dest-ipv4-address {
              leaf dest-ipv4-prefix {
                type inet:ipv4-prefix;
                mandatory true;
                description
                  "An IPv4 destination address as the match.";
              }
            }
            case src-ipv4-address {
              leaf src-ipv4-prefix {
                type inet:ipv4-prefix;
                mandatory true;
                description
                  "An IPv4 source address as the match.";
              }
            }
            case dest-src-ipv4-address {
              container dest-src-ipv4-address {
                description
                  "A combination of an IPv4 source and
                   an IPv4 destination address as the match.";
                leaf dest-ipv4-prefix {
                  type inet:ipv4-prefix;
                  mandatory true;
                  description
                    "The IPv4 destination address of the match.";
                }
                leaf src-ipv4-prefix {
                  type inet:ipv4-prefix;
                  mandatory true;
                  description
                    "The IPv4 source address of the match.";
                }
              }
            }
          }
        }
      }
      case ipv6 {
        description
          "IPv6 route case.";
        container ipv6 {
          description
            "IPv6 route match.";
          choice ip-route-match-type {
            description
              "IP route match type options:
               match source,
               match destination, or
               match source and destination.";
            case dest-ipv6-address {
              leaf dest-ipv6-prefix {

                type inet:ipv6-prefix;
                mandatory true;
                description
                  "An IPv6 destination address as the match.";
              }
            }
            case src-ipv6-address {
              leaf src-ipv6-prefix {
                type inet:ipv6-prefix;
                mandatory true;
                description
                  "An IPv6 source address as the match.";
              }
            }
            case dest-src-ipv6-address {
              container dest-src-ipv6-address {
                description
                  "A combination of an IPv6 source and
                   an IPv6 destination address as the match.";
                leaf dest-ipv6-prefix {
                  type inet:ipv6-prefix;
                  mandatory true;
                  description
                    "The IPv6 destination address of the match.";
                }
                leaf src-ipv6-prefix {
                  type inet:ipv6-prefix;
                  mandatory true;
                  description
                    "The IPv6 source address of the match.";
                }
              }
            }
          }
        }
      }
      case mpls-route {
        description
          "MPLS route case.";
        leaf mpls-label {
          type uint32;
          mandatory true;
          description
            "The label used for matching.";
        }
      }
      case mac-route {
        description

          "MAC route case.";
        leaf mac-address {
          type yang:mac-address;
          mandatory true;
          description
            "The MAC address used for matching.";
        }
      }
      case interface-route {
        description
          "Interface route case.";
        leaf interface-identifier {
          type if:interface-ref;
          mandatory true;
          description
            "The interface used for matching.";
        }
      }
    }
  }
}

grouping route {
  description
    "The common attributes used for all types of routes.";
  uses route-prefix;
  container nexthop {
    description
      "The nexthop of the route.";
    uses nexthop;
  }
  //In the information model, it is called route-statistic
  container route-status {
    description
      "The status information of the route.";
    leaf route-state {
      type route-state-definition;
      config false;
      description
        "Indicate a route's state: active or inactive.";
    }
    leaf route-installed-state {
      type route-installed-state-definition;
      config false;
      description
        "Indicate that a route's installed states:
         installed or uninstalled.";
    }
    leaf route-reason {
      type route-change-reason-definition;
      config false;
      description
        "Indicate the reason that caused the route change.";
    }
  }
  container route-attributes {
    description
      "Route attributes.";
    uses route-attributes;
  }
  container route-vendor-attributes {
    description
      "Route vendor attributes.";
    uses route-vendor-attributes;
  }
}

grouping nexthop-list {
  description
    "A generic nexthop list.";
  list nexthop-list {
    key "nexthop-member-id";
    description
      "A list of nexthops.";
    leaf nexthop-member-id {
      type uint32;
      mandatory true;
      description
        "A nexthop identifier that points
         to a nexthop list member.
         A nexthop list member is a nexthop.";
    }
  }
}

grouping nexthop-list-p {
  description
    "A nexthop list with preference parameter.";
  list nexthop-list {
    key "nexthop-member-id";
    description
      "A list of nexthop.";
    leaf nexthop-member-id {
      type uint32;
      mandatory true;
      description
             "A nexthop identifier that points
              to a nexthop list member.
              A nexthop list member is a nexthop.";
         }
         leaf nexthop-preference {
           type nexthop-preference-definition;
           mandatory true;
           description
             "Nexthop-preference is used for protection schemes.
              It is an integer value between 1 and 99.  Lower
              values are more preferred.  To download a
              primary/standby/tertiary group to the FIB, the
              nexthops that are resolved and are most preferred
              are selected.";
         }
       }
     }

     grouping nexthop-list-w {
       description
         "A nexthop list with a weight parameter.";
       list nexthop-list {
         key "nexthop-member-id";
         description
           "A list of nexthop.";
         leaf nexthop-member-id {
           type uint32;
           mandatory true;
           description
             "A nexthop identifier that points
              to a nexthop list member.
              A nexthop list member is a nexthop.";
         }
         leaf nexthop-lb-weight {
           type nexthop-lb-weight-definition;
           mandatory true;
           description
             "The weight of a nexthop of
              the load-balance nexthops.";
         }
       }
     }

Okay so the nexthop-preference leaf is giving protection-scheme energy πŸ›‘οΈβœ¨ It's an integer from 1 to 99, and lower means more preferred, so bestie, think of it like a VIP line where the smaller number gets in first πŸ‘‘

Now the main event, the nexthop grouping. It's the whole nexthop structure, and it's where all the different nexthop types live together πŸ’…

     grouping nexthop {
       description
         "The nexthop structure.";
       leaf nexthop-id {
         type uint32;
         description
           "An identifier that refers to a nexthop.";
       }
       leaf sharing-flag {
         type boolean;
         description
           "To indicate whether a nexthop is sharable
            or non-sharable:
            true  - sharable (which means the nexthop can be
                    shared with other routes)
            false - non-sharable (which means the nexthop can
                    not be shared with other routes)";
       }
       choice nexthop-type {
         description
           "Nexthop type options.";
         case nexthop-base {
           container nexthop-base {
             description
               "The base nexthop.";
             uses nexthop-base;
           }
         }
         case nexthop-chain {
           if-feature "nexthop-chain";
           container nexthop-chain {
             description
               "A chain nexthop.";
             uses nexthop-list;
           }
         }
         case nexthop-replicate {
           if-feature "nexthop-replicate";
           container nexthop-replicate {
             description
               "A replicate nexthop.";
             uses nexthop-list;
           }
         }
         case nexthop-protection {
           if-feature "nexthop-protection";
           container nexthop-protection {
             description
               "A protection nexthop.";
             uses nexthop-list-p;
           }
         }
         case nexthop-load-balance {

           if-feature "nexthop-load-balance";
           container nexthop-lb {
             description
               "A load-balance nexthop.";
             uses nexthop-list-w;
           }
         }
       }
     }

The sharing-flag is a boolean, so it's basically a yes-or-no on whether a nexthop can be shared with other routes. Honestly, the choice nexthop-type is my favourite part, because it's a whole buffet of options πŸ“ Each case is wrapped in its own container, and a few of them only show up if their feature is turned on, so if-feature is doing a lot of gatekeeping here πŸ™ˆ

Next up is the nexthop-base grouping. This is where the base nexthop types get their own little cases, from special nexthops to egress interfaces, addresses, tunnels and RIB chaining πŸ¦‹

     grouping nexthop-base {
       description
         "The base nexthop.";
       choice nexthop-base-type {
         description
           "Nexthop base type options.";
         case special-nexthop {
           leaf special {
             type special-nexthop-definition;
             description
               "A special nexthop.";
           }
         }
         case egress-interface-nexthop {
           leaf outgoing-interface {
             type if:interface-ref;
             mandatory true;
             description
               "The nexthop is an outgoing interface.";
           }
         }
         case ipv4-address-nexthop {
           leaf ipv4-address {
             type inet:ipv4-address;
             mandatory true;
             description
               "The nexthop is an IPv4 address.";
           }
         }
         case ipv6-address-nexthop {
           leaf ipv6-address {
             type inet:ipv6-address;
             mandatory true;
             description
               "The nexthop is an IPv6 address.";
           }
         }
         case egress-interface-ipv4-nexthop {

           container egress-interface-ipv4-address {
             leaf outgoing-interface {
               type if:interface-ref;
               mandatory true;
               description
                 "Name of the outgoing interface.";
             }
             leaf ipv4-address {
               type inet:ipv4-address;
               mandatory true;
               description
                 "The nexthop points to an interface with
                  an IPv4 address.";
             }
             description
               "The nexthop is an egress-interface and an IP
                address.  This can be used in cases where, e.g.,
                the IP address is a link-local address.";
           }
         }
         case egress-interface-ipv6-nexthop {
           container egress-interface-ipv6-address {
             leaf outgoing-interface {
               type if:interface-ref;
               mandatory true;
               description
                 "Name of the outgoing interface.";
             }
             leaf ipv6-address {
               type inet:ipv6-address;
               mandatory true;
               description
                 "The nexthop points to an interface with
                  an IPv6 address.";
             }
             description
               "The nexthop is an egress-interface and an IP
                address.  This can be used in cases where, e.g.,
                the IP address is a link-local address.";
           }
         }
         case egress-interface-mac-nexthop {
           container egress-interface-mac-address {
             leaf outgoing-interface {
               type if:interface-ref;
               mandatory true;
               description
                 "Name of the outgoing interface.";

             }
             leaf ieee-mac-address {
               type yang:mac-address;
               mandatory true;
               description
                 "The nexthop points to an interface with
                  a specific MAC address.";
             }
             description
               "The egress-interface must be an Ethernet
                interface.  Address resolution is not required
                for this nexthop.";
           }
         }
         case tunnel-encapsulation-nexthop {
           if-feature "nexthop-tunnel";
           container tunnel-encapsulation {
             uses tunnel-encapsulation;
             description
               "This can be an encapsulation representing an IP
                tunnel, MPLS tunnel, or others as defined in the info
                model.  An optional egress-interface can be chained
                to the tunnel encapsulation to indicate which
                interface to send the packet out on.  The
                egress-interface is useful when the network device
                contains Ethernet interfaces and one needs to
                perform address resolution for the IP packet.";
           }
         }
         case tunnel-decapsulation-nexthop {
           if-feature "nexthop-tunnel";
           container tunnel-decapsulation {
             uses tunnel-decapsulation;
             description
               "This is to specify the decapsulation of a tunnel
                header.";
           }
         }
         case logical-tunnel-nexthop {
           if-feature "nexthop-tunnel";
           container logical-tunnel {
             uses logical-tunnel;
             description
               "This can be an MPLS Label Switched Path (LSP)
                or a GRE tunnel (or others as defined in this
                document) that is represented by a unique
                identifier (e.g., name).";
           }

         }
         case rib-name-nexthop {
           leaf rib-name {
             type string;
             description
               "A nexthop pointing to a RIB indicates that the
                route lookup needs to continue in the specified
                RIB.  This is a way to perform chained lookups.";
           }
         }
         case nexthop-identifier {
           leaf nexthop-ref {
             type nexthop-ref;
             mandatory true;
             description
               "A nexthop reference that points to a nexthop.";
           }
         }
       }
     }

Okay the rib-name-nexthop case is lowkey my fave 🧚 A nexthop that points to a RIB means the lookup keeps going in that other RIB, so it's basically chained lookups, which is so iconic for multi-step routing πŸ’œ

Last stretch! These are the leftover groupings: vendor attributes (empty for now, very mysterious πŸŒ™), the logical tunnel, and the IPv4 and IPv6 header encapsulation info πŸŽ€

     grouping route-vendor-attributes {
       description
         "Route vendor attributes.";
     }

     grouping logical-tunnel {
       description
         "A logical tunnel that is identified
          by a type and a tunnel name.";
       leaf tunnel-type {
         type tunnel-type-definition;
         mandatory true;
         description
           "A tunnel type.";
       }
       leaf tunnel-name {
         type string;
         mandatory true;
         description
           "A tunnel name that points to a logical tunnel.";
       }
     }

     grouping ipv4-header {
       description
         "The IPv4 header encapsulation information.";
       leaf src-ipv4-address {

         type inet:ipv4-address;
         mandatory true;
         description
           "The source IP address of the header.";
       }
       leaf dest-ipv4-address {
         type inet:ipv4-address;
         mandatory true;
         description
           "The destination IP address of the header.";
       }
       leaf protocol {
         type uint8;
         mandatory true;
         description
           "The protocol id of the header.";
       }
       leaf ttl {
         type uint8;
         description
           "The TTL of the header.";
       }
       leaf dscp {
         type uint8;
         description
           "The Differentiated Services Code Point
            (DSCP) field of the header.";
       }
     }

     grouping ipv6-header {
       description
         "The IPv6 header encapsulation information.";
       leaf src-ipv6-address {
         type inet:ipv6-address;
         mandatory true;
         description
           "The source IP address of the header.";
       }
       leaf dest-ipv6-address {
         type inet:ipv6-address;
         mandatory true;
         description
           "The destination IP address of the header.";
       }
       leaf next-header {
         type uint8;
         mandatory true;
         description
           "The next header of the IPv6 header.";
       }
       leaf traffic-class {
         type uint8;
         description
           "The traffic class value of the header.";
       }
       leaf flow-label {
         type inet:ipv6-flow-label;
         description
           "The flow label of the header.";
       }
       leaf hop-limit {
         type uint8 {
           range "1..255";
         }
         description
           "The hop limit of the header.";
       }
     }

Bestie, the hop-limit leaf is restricted to a range of 1 to 255, and that's the kind of detail that makes me obsessed 😭🫢 The header groupings are where the encapsulation info lives, so they're giving very organised main character energy ✨

okay bestie, the encapsulation groupings are next πŸŽ€ NVGRE, VXLAN, GRE, MPLS, all the tunnel stuff. The cases in each choice decide which header shape you're getting ✨

     grouping nvgre-header {
       description
         "The NVGRE header encapsulation information.";
       choice nvgre-type {
         description
           "NVGRE can use either an IPv4
            or an IPv6 header for encapsulation.";
         case ipv4 {
           uses ipv4-header;
         }
         case ipv6 {
           uses ipv6-header;
         }
       }
       leaf virtual-subnet-id {
         type uint32;
         mandatory true;
         description
           "The subnet identifier of the NVGRE header.";
       }
       leaf flow-id {
         type uint8;
         description
           "The flow identifier of the NVGRE header.";
       }
     }
     grouping vxlan-header {
       description
         "The VXLAN encapsulation header information.";
       choice vxlan-type {
         description
           "NVGRE can use either an IPv4
            or an IPv6 header for encapsulation.";
         case ipv4 {
           uses ipv4-header;
         }
         case ipv6 {
           uses ipv6-header;
         }
       }
       leaf vxlan-identifier {
         type uint32;
         mandatory true;
         description
           "The VXLAN identifier of the VXLAN header.";
       }
     }

     grouping gre-header {
       description
         "The GRE encapsulation header information.";
       choice dest-address-type {
         description
           "GRE options: IPv4 and IPv6";
         case ipv4 {
           leaf ipv4-dest {
             type inet:ipv4-address;
             mandatory true;
             description
               "The destination IP address of the GRE header.";
           }
         }
         case ipv6 {
           leaf ipv6-dest {
             type inet:ipv6-address;
             mandatory true;
             description
               "The destination IP address of the GRE header.";
           }
         }
       }
       leaf protocol-type {
         type uint16;
         mandatory true;
         description
           "The protocol type of the GRE header.";
       }
       leaf key {
         type uint64;
         description
           "The GRE key of the GRE header.";
       }
     }

     grouping mpls-header {
       description
         "The MPLS encapsulation header information.";
       list label-operations {
         key "label-oper-id";
         description
           "Label operations.";
         leaf label-oper-id {
           type uint32;
           description
             "An optional identifier that points
              to a label operation.";
         }
         choice label-actions {
           description
             "Label action options.";
           case label-push {
             container label-push {
               description
                 "Label push operation.";
               leaf label {
                 type uint32;
                 mandatory true;
                 description
                   "The label to be pushed.";
               }
               leaf s-bit {
                 type boolean;
                 description
                   "The s-bit ('Bottom of Stack' bit) of the label to be
                    pushed.";
               }
               leaf tc-value {
                 type uint8;
                 description
                   "The traffic class value of the label to be pushed.";
               }
               leaf ttl-value {

                 type uint8;
                 description
                   "The TTL value of the label to be pushed.";
               }
             }
           }
           case label-swap {
             container label-swap {
               description
                 "Label swap operation.";
               leaf in-label {
                 type uint32;
                 mandatory true;
                 description
                   "The label to be swapped.";
               }
               leaf out-label {
                 type uint32;
                 mandatory true;
                 description
                   "The out MPLS label.";
               }
               leaf ttl-action {
                 type ttl-action-definition;
                 description
                   "The label TTL actions:
                    - No-action
                    - Copy to inner label
                    - Decrease (the in-label)
                      by 1 and copy to the out-label";
               }
             }
           }
         }
       }
     }

next up: the tunnel-encapsulation and tunnel-decapsulation groupings, where every case is gated behind an if-feature πŸ¦‹

     grouping tunnel-encapsulation {
       description
         "Tunnel encapsulation information.";
       choice tunnel-type {
         description
           "Tunnel options for nexthops.";
         case ipv4 {
           if-feature "ipv4-tunnel";
           container ipv4-header {
             uses ipv4-header;
             description

               "IPv4 header.";
           }
         }
         case ipv6 {
           if-feature "ipv6-tunnel";
           container ipv6-header {
             uses ipv6-header;
             description
               "IPv6 header.";
           }
         }
         case mpls {
           if-feature "mpls-tunnel";
           container mpls-header {
             uses mpls-header;
             description
               "MPLS header.";
           }
         }
         case gre {
           if-feature "gre-tunnel";
           container gre-header {
             uses gre-header;
             description
               "GRE header.";
           }
         }
         case nvgre {
           if-feature "nvgre-tunnel";
           container nvgre-header {
             uses nvgre-header;
             description
               "NVGRE header.";
           }
         }
         case vxlan {
           if-feature "vxlan-tunnel";
           container vxlan-header {
             uses vxlan-header;
             description
               "VXLAN header.";
           }
         }
       }
     }

     grouping tunnel-decapsulation {
       description

         "Tunnel decapsulation information.";
       choice tunnel-type {
         description
           "Nexthop tunnel type options.";
         case ipv4 {
           if-feature "ipv4-tunnel";
           container ipv4-decapsulation {
             description
               "IPv4 decapsulation.";
             leaf ipv4-decapsulation {
               type tunnel-decapsulation-action-definition;
               mandatory true;
               description
                 "IPv4 decapsulation operations.";
             }
             leaf ttl-action {
               type ttl-action-definition;
               description
                 "The TTL actions:
                  no-action or copy to inner header.";
             }
           }
         }
         case ipv6 {
           if-feature "ipv6-tunnel";
           container ipv6-decapsulation {
             description
               "IPv6 decapsulation.";
             leaf ipv6-decapsulation {
               type tunnel-decapsulation-action-definition;
               mandatory true;
               description
                 "IPv6 decapsulation operations.";
             }
             leaf hop-limit-action {
               type hop-limit-action-definition;
               description
                 "The hop limit actions:
                  no-action or copy to inner header.";
             }
           }
         }
         case mpls {
           if-feature "mpls-tunnel";
           container label-pop {
             description
               "MPLS decapsulation.";
             leaf label-pop {

               type mpls-label-action-definition;
               mandatory true;
               description
                 "Pop a label from the label stack.";
             }
             leaf ttl-action {
               type ttl-action-definition;
               description
                 "The label TTL action.";
             }
           }
         }
       }
     }

last stretch of this chunk: route attributes, the routing-instance container, and the RPC marker πŸ’…

     grouping route-attributes {
       description
         "Route attributes.";
       leaf route-preference {
         type uint32;
         mandatory true;
         description
           "ROUTE_PREFERENCE: This is a numerical value that
            allows for comparing routes from different
            protocols.  Static configuration is also
            considered a protocol for the purpose of this
            field.  It is also known as administrative-distance.
            The lower the value, the higher the preference.";
       }
       leaf local-only {
         type boolean;
         mandatory true;
         description
           "Indicate whether the attribute is local only.";
       }
       container address-family-route-attributes {
         description
           "Address-family-related route attributes.";
         choice route-type {
           description
             "Address-family-related route attributes. Future
              documents should specify these attributes by augmenting
              the cases in this choice.";
           case ip-route-attributes {
           }
           case mpls-route-attributes {
           }
           case ethernet-route-attributes {
           }
         }
       }
     }

     container routing-instance {
       description
         "A routing instance, in the context of
          the RIB information model, is a collection
          of RIBs, interfaces, and routing parameters.";
       leaf name {
         type string;
         description
           "The name of the routing instance.  This MUST
            be unique across all routing instances in
            a given network device.";
       }
       list interface-list {
         key "name";
         description
           "This represents the list of interfaces associated
            with this routing instance.  The interface list helps
            constrain the boundaries of packet forwarding.
            Packets coming on these interfaces are directly
            associated with the given routing instance.  The
            interface list contains a list of identifiers with
            each identifier uniquely identifying an interface.";
         leaf name {
           type if:interface-ref;
           description
             "A reference to the name of a network-layer interface.";
         }
       }
       leaf router-id {
         type yang:dotted-quad;
         description
           "Router ID: The 32-bit number in the form of a dotted quad.";
       }
       leaf lookup-limit {
         type uint8;
         description
           "A limit on how many levels of a lookup can be performed.";
       }
       list rib-list {
         key "name";
         description
           "A list of RIBs that are associated with the routing
            instance.";

         leaf name {
           type string;
           mandatory true;
           description
             "A reference to the name of each RIB.";
         }
         leaf address-family {
           type address-family-definition;
           mandatory true;
           description
             "The address family of a RIB.";
         }
         leaf ip-rpf-check {
           type boolean;
           description
             "Each RIB can be optionally associated with a
              ENABLE_IP_RPF_CHECK attribute that enables Reverse
              Path Forwarding (RPF) checks on all IP routes in that
              RIB.   An RPF check is used to
              prevent spoofing and limit malicious traffic.";
         }
         list route-list {
           key "route-index";
           description
             "A list of routes of a RIB.";
           uses route;
         }
         // This is a list that maintains the nexthops added to the RIB.
         uses nexthop-list;
       }
     }

     //RPC Operations

okay so bestie, this is where the RPC operations get spicy πŸ’… we're adding RIBs, deleting RIBs, and then the route ops start rolling in like a whole group chat πŸ¦‹

Let's start with rib-add, the RPC that adds a RIB to an instance. It takes a name, an address-family, and an optional ip-rpf-check flag. The ip-rpf-check leaf is the one that turns on RPF checks for all IP routes in that RIB, and the description says it's there to stop spoofing and limit malicious traffic πŸ›‘οΈβœ¨ Output-wise it hands back a result boolean and a reason string if things go sideways πŸ™ˆ

     rpc rib-add {
       description
         "To add a RIB to an instance";
       input {
         leaf name {
           type string;
           mandatory true;
           description
             "A reference to the name of the RIB
              that is to be added.";
         }
         leaf address-family {
           type address-family-definition;
           mandatory true;
           description
             "The address family of the RIB.";
         }
         leaf ip-rpf-check {
           type boolean;
           description
             "Each RIB can be optionally associated with an
              ENABLE_IP_RPF_CHECK attribute that enables
              RPF checks on all IP routes in that
              RIB.   An RPF check is used to
              prevent spoofing and limit malicious traffic.";
         }
       }
       output {
         leaf result {
           type boolean;
           mandatory true;
           description
             "Return the result of the rib-add operation.
              true  - success;
              false - failed";
         }
         leaf reason {
           type string;
           description
             "The specific reason that caused the failure.";
         }
       }
     }

Next up is rib-delete, which removes a RIB from a routing instance. This one is a little dramatic 😭 because the description says that once the RIB is gone, every route installed in it gets deleted too. So be careful, bestie πŸ₯Ί It only needs a name in the input, and the output mirrors rib-add with a result and an optional reason.

     rpc rib-delete {
       description
         "To delete a RIB from a routing instance.
          After deleting the RIB, all routes installed
          in the RIB will be deleted as well.";
       input {
         leaf name {
           type string;
           mandatory true;
           description
             "A reference to the name of the RIB
              that is to be deleted.";
         }
       }
       output {
         leaf result {
           type boolean;
           mandatory true;
           description
             "Return the result of the rib-delete operation.
              true  - success;
              false - failed";
         }
         leaf reason {
           type string;
           description
             "The specific reason that caused failure.";
         }
       }
     }

Now we get to the route-operation-state grouping πŸŽ€ This is the shared output shape that the route add, delete, and update RPCs all reuse. It tracks a success-count and a failed-count, both uint32 and both mandatory. Then there's a failure-detail container with a failed-routes list, keyed by route-index. Each entry has the route-index and an error-code. The error codes are where it gets iconic: 0 is reserved, 1 means you tried to add a repeat route, 2 means you tried to delete or update a route that doesn't exist, and 3 means the route attributes were malformed πŸ’€

     grouping route-operation-state {
       description
         "Route operation state.";
       leaf success-count {
         type uint32;
         mandatory true;
         description
           "The numbers of routes that are successfully
            added/deleted/updated.";
       }
       leaf failed-count {
         type uint32;
         mandatory true;
         description
           "The numbers of the routes that fail
            to be added/deleted/updated.";
       }
       container failure-detail {
         description
           "The failure detail reflects the reason why a route
            operation fails.  It is an array that includes the route
            index and error code of the failed route.";
         list failed-routes {
           key "route-index";
           description
             "The list of failed routes.";
           leaf route-index {
             type uint32;
             description
               "The route index of the failed route.";
           }
           leaf error-code {
             type uint32;
             description
               "The error code that reflects the failure reason.

                0 - Reserved
                1 - Trying to add a repeat route
                2 - Trying to delete or update a route that does not
                  exist
                3 - Malformed route attributes";
           }
         }
       }
     }

Time for route-add ✨ This is the RPC that adds a route, or a whole list of routes, to a RIB. It has a return-failure-detail boolean that defaults to false, which decides whether the failure details come back. It also needs a rib-name, and then there's a routes container holding a route-list keyed by route-index. Each route in that list brings its prefix, its route-attributes, and optionally route-vendor-attributes (that one is gated behind the route-vendor-attributes feature, so it's giving optional but iconic). Every route can also carry a nexthop. The output just uses the shared route-operation-state grouping we just looked at 🌸

     rpc route-add {
       description
         "To add a route or a list of routes to a RIB";
       input {
         leaf return-failure-detail {
           type boolean;
           default "false";
           description
             "Whether to return the failure detail.
              true  - return the failure detail
              false - do not return the failure detail
              The default is false.";
         }
         leaf rib-name {
           type string;
           mandatory true;
           description
             "A reference to the name of a RIB.";
         }
         container routes {
           description
             "The routes to be added to the RIB.";
           list route-list {
             key "route-index";
             description
               "The list of routes to be added.";
             uses route-prefix;
             container route-attributes {
               uses route-attributes;
               description
                 "The route attributes.";
             }
             container route-vendor-attributes {
               if-feature "route-vendor-attributes";
               uses route-vendor-attributes;
               description
                 "The route vendor attributes.";
             }
             container nexthop {
               uses nexthop;
               description
                 "The nexthop of the added route.";
             }
           }
         }
       }
       output {
         uses route-operation-state;
       }
     }

Next is route-delete, which is basically the same vibe as route-add but way more chill πŸ¦‹ You give it a return-failure-detail flag, a rib-name, and a list of routes identified by their prefixes. No attributes, no nexthop, just the prefix. Output is again the shared route-operation-state grouping. (The description on the routes container still says "to be added to the RIB," which is a copy-paste leftover in the original, so I'm keeping it exactly as written. Not me making a change to the spec πŸ™ˆ)

     rpc route-delete {
       description
         "To delete a route or a list of routes from a RIB";
       input {
         leaf return-failure-detail {
           type boolean;
           default "false";
           description
             "Whether to return the failure detail.
              true  - return the failure detail
              false - do not return the failure detail
              The default is false.";
         }
         leaf rib-name {
           type string;
           mandatory true;
           description
             "A reference to the name of a RIB.";
         }
         container routes {
           description
             "The routes to be added to the RIB.";
           list route-list {
             key "route-index";
             description
               "The list of routes to be deleted.";
             uses route-prefix;
           }
         }
       }
       output {
         uses route-operation-state;
       }
     }
     grouping route-update-options {
       description
         "Update options:
          1. update the nexthop
          2. update the route attributes
          3. update the route-vendor-attributes";
       choice update-options {
         description
           "Update options:
            1. update the nexthop
            2. update the route attributes
            3. update the route-vendor-attributes";
         case update-nexthop {
           container updated-nexthop {
             uses nexthop;
             description
               "The nexthop used for updating.";
           }
         }
         case update-route-attributes {
           container updated-route-attr {
             uses route-attributes;
             description
               "The route attributes used for updating.";
           }
         }
         case update-route-vendor-attributes {
           container updated-route-vendor-attr {
             uses route-vendor-attributes;
             description
               "The vendor route attributes used for updating.";
           }
         }
       }
     }

Here's the route-update-options grouping, which is the "what do I change?" menu πŸ“ It's a choice with three cases: update the nexthop, update the route attributes, or update the route-vendor-attributes. You pick one, and the matching container holds the new value.

Last for this part is route-update πŸŽ€ It's the most complex RPC so far, because it has to figure out which routes to touch before it can update anything. The rib-name and return-failure-detail are the usual suspects. The big thing is the match-options choice, which lets you find routes by route-prefix, by route-attributes, by route-vendor-attributes (feature-gated, obviously), or by nexthop. Each case has its own way of carrying the update parameters, and they all reuse the route-update-options grouping we just saw. The description also spells out the inputs, the actions, and the outputs (success-count, failed-count, and failure-detail), so it's basically the RPC's own little cheat sheet ✨

     rpc route-update {
       description
         "To update a route or a list of routes of a RIB.
          The inputs:
            1. The match conditions, which could be:
              a. route prefix,
              b. route attributes, or
              c. nexthop.
            2. The update parameters to be used:
              a. new nexthop,
              b. new route attributes, or
              c. nexthop.

          Actions:
            1. update the nexthop
            2. update the route attributes
          The outputs:
            success-count - the number of routes updated
            failed-count - the number of routes fail to update
            failure-detail - the detail failure info
         ";
       input {
         leaf return-failure-detail {
           type boolean;
           default "false";
           description
             "Whether to return the failure detail.
              true  - return the failure detail
              false - do not return the failure detail
              The default is false.";
         }
         leaf rib-name {
           type string;
           mandatory true;
           description
             "A reference to the name of a RIB.";
         }
         choice match-options {
           description
             "Match options.";
           case match-route-prefix {
             description
               "Update the routes that match the route
                prefix(es) condition.";
             container input-routes {
               description
                 "The matched routes to be updated.";
               list route-list {
                 key "route-index";
                 description
                   "The list of routes to be updated.";
                 uses route-prefix;
                 uses route-update-options;
               }
             }
           }
           case match-route-attributes {
             description
               "Update the routes that match the
                route attributes condition.";
             container input-route-attributes {

               description
                 "The route attributes are used for matching.";
               uses route-attributes;
             }
             container update-parameters {
               description
                 "Update options:
                  1. update the nexthop
                  2. update the route attributes
                  3. update the route-vendor-attributes";
               uses route-update-options;
             }
           }
           case match-route-vendor-attributes {
             if-feature "route-vendor-attributes";
             description
               "Update the routes that match the
                vendor attributes condition";
             container input-route-vendor-attributes {
               description
                 "The vendor route attributes are used for matching.";
               uses route-vendor-attributes;
             }
             container update-parameters-vendor {
               description
                 "Update options:
                  1. update the nexthop
                  2. update the route attributes
                  3. update the route-vendor-attributes";
               uses route-update-options;
             }
           }
           case match-nexthop {
             description
               "Update the routes that match the nexthop.";
             container input-nexthop {
               description
                 "The nexthop used for matching.";
               uses nexthop;
             }
             container update-parameters-nexthop {
               description
                 "Update options:
                  1. update the nexthop
                  2. update the route attributes
                  3. update the route-vendor-attributes";
               uses route-update-options;
             }
           }
         }
       }
       output {
         uses route-operation-state;
       }
     }
     rpc nh-add {
       description
         "To add a nexthop to a RIB.
          Inputs parameters:
            1. rib-name
            2. nexthop
          Actions:
            Add the nexthop to the RIB
          Outputs:
            1. Operation result:
               true  - success
               false - failed
            2. nexthop identifier";
       input {
         leaf rib-name {
           type string;
           mandatory true;
           description
             "A reference to the name of a RIB.";
         }
         uses nexthop;
       }
       output {
         leaf result {
           type boolean;
           mandatory true;
           description
             "Return the result of the rib-add operation:
              true  - success
              false - failed";
         }
         leaf reason {
           type string;
           description
             "The specific reason that caused the failure.";
         }
         leaf nexthop-id {
           type uint32;
           description
             "A nexthop identifier that is allocated to the nexthop.";
         }

       }
     }

     rpc nh-delete {
       description
         "To delete a nexthop from a RIB";
       input {
         leaf rib-name {
           type string;
           mandatory true;
           description
             "A reference to the name of a RIB.";
         }
         uses nexthop;
       }
       output {
         leaf result {
           type boolean;
           mandatory true;
           description
             "Return the result of the rib-add operation:
              true  - success;
              false - failed";
         }
         leaf reason {
           type string;
           description
             "The specific reason that caused the failure.";
         }
       }
     }

     //Notifications

     notification nexthop-resolution-status-change {
       description
         "Nexthop resolution status (resolved/unresolved)
          notification.";
       container nexthop {
         description
           "The nexthop.";
         uses nexthop;
       }
       leaf nexthop-state {
         type nexthop-state-definition;
         mandatory true;
         description
           "Nexthop resolution status (resolved/unresolved)

            notification.";
       }
     }

     notification route-change {
       description
         "Route change notification.";
       leaf rib-name {
         type string;
         mandatory true;
         description
           "A reference to the name of a RIB.";
       }
       leaf address-family {
         type address-family-definition;
         mandatory true;
         description
           "The address family of a RIB.";
       }
       uses route-prefix;
       leaf route-installed-state {
         type route-installed-state-definition;
         mandatory true;
         description
           "Indicates whether the route got installed in the FIB.";
       }
       leaf route-state {
         type route-state-definition;
         mandatory true;
         description
           "Indicates whether a route is active or inactive.";
       }
       list route-change-reasons {
         key "route-change-reason";
         description
           "The reasons that cause the route change.  A route
            change may result from several reasons; for
            example, a nexthop becoming resolved will make a
            route A active, which is of better preference than
            a currently active route B, which results in the
            route A being installed";
         leaf route-change-reason {
           type route-change-reason-definition;
           mandatory true;
           description
             "The reason that caused the route change.";
         }
       }

     }
   }

<CODE ENDS>


4. IANA Considerations ✨

okay so IANA gets two registrations from this document πŸŽ€ The first one is a URI that goes into the "ns" registry within the "IETF XML Registry" [RFC3688]:

    -------------------------------------------------------------------
    URI: urn:ietf:params:xml:ns:yang:ietf-i2rs-rib
    Registrant Contact: The IESG.
    XML: N/A, the requested URI is an XML namespace.
    -------------------------------------------------------------------

The second one is the YANG module itself, which goes into the "YANG Module Names" registry [RFC7950] πŸ’…:

    -------------------------------------------------------------------
    name:         ietf-i2rs-rib
    namespace:    urn:ietf:params:xml:ns:yang:ietf-i2rs-rib
    prefix:       iir
    reference:    RFC 8431
    -------------------------------------------------------------------

5. Security Considerations 🚨

okay bestie, this one is SERIOUS 😭 please read it like your network depends on it, because it kinda does πŸ’€

So the YANG module is basically a schema for data that's meant to be reached through network management protocols like NETCONF [RFC6241] or RESTCONF [RFC8040]. For NETCONF, the lowest layer is the secure transport layer, and the mandatory-to-implement secure transport is Secure Shell (SSH) [RFC6242]. For RESTCONF, the lowest layer is HTTPS, and the mandatory-to-implement secure transport is TLS [RFC8446]. ✨

The NETCONF access control model [RFC8341] is the thing that lets you restrict particular NETCONF or RESTCONF users to a preconfigured subset of all the available NETCONF or RESTCONF protocol operations and content. It's giving bouncer at the club 🧚

Now the scary part πŸ™ˆ. The module defines information that can be configured in certain cases. For example, a RIB, a route, or a nexthop can be created or deleted by client applications. The module also defines RPCs that client applications can use to add or delete RIBs, routes, and nexthops. So a malicious client could try to remove, add, or update a RIB, a route, or a nexthop by creating or deleting the matching elements in the RIB, route, and nexthop lists, respectively. Removing a RIB or a route could cause disruption or hurt the performance of a service. Updating a route might lead to a suboptimal path and degraded service levels, and possibly disruption of service too. That's why it's super important that the NETCONF access control model is vigorously applied, so unauthorized clients can't cause misconfiguration πŸ”’

There are a bunch of data nodes in this module that are writable, creatable, and deletable (that's config true, which is the default). These data nodes may be considered sensitive or vulnerable in some network environments. Write operations (like edit-config) to these data nodes without proper protection can have a negative effect on network operations. Here are the subtrees and data nodes, plus how sensitive or vulnerable each one is:

  • RIB: A malicious client could try to remove a RIB from a routing instance, for example to sabotage the services the RIB provides, or to add a RIB to a routing instance (and therefore inject unauthorized traffic into the nexthop). 😀
  • route: A malicious client could try to remove or add a route from or to a RIB, for example to sabotage the services the RIB provides. πŸ₯€
  • nexthop: A malicious client could try to remove or add a nexthop from or to a RIB, which may lead to a suboptimal path, a degradation of service levels, and a possible disruption of service. πŸ’€

6. References πŸ“š

6.1. Normative References

[RFC2119]  Bradner, S., "Key words for use in RFCs to Indicate
           Requirement Levels", BCP 14, RFC 2119,
           DOI 10.17487/RFC2119, March 1997,
           <https://www.rfc-editor.org/info/rfc2119>.

[RFC3688]  Mealling, M., "The IETF XML Registry", BCP 81, RFC 3688,
           DOI 10.17487/RFC3688, January 2004,
           <https://www.rfc-editor.org/info/rfc3688>.

[RFC6241]  Enns, R., Ed., Bjorklund, M., Ed., Schoenwaelder, J., Ed.,
           and A. Bierman, Ed., "Network Configuration Protocol
           (NETCONF)", RFC 6241, DOI 10.17487/RFC6241, June 2011,
           <https://www.rfc-editor.org/info/rfc6241>.

[RFC6242]  Wasserman, M., "Using the NETCONF Protocol over Secure
           Shell (SSH)", RFC 6242, DOI 10.17487/RFC6242, June 2011,
           <https://www.rfc-editor.org/info/rfc6242>.

[RFC6991]  Schoenwaelder, J., Ed., "Common YANG Data Types",
           RFC 6991, DOI 10.17487/RFC6991, July 2013,
           <https://www.rfc-editor.org/info/rfc6991>.

[RFC7950]  Bjorklund, M., Ed., "The YANG 1.1 Data Modeling Language",
           RFC 7950, DOI 10.17487/RFC7950, August 2016,
           <https://www.rfc-editor.org/info/rfc7950>.

[RFC8040]  Bierman, A., Bjorklund, M., and K. Watsen, "RESTCONF
           Protocol", RFC 8040, DOI 10.17487/RFC8040, January 2017,
           <https://www.rfc-editor.org/info/rfc8040>.

[RFC8174]  Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC
           2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174,
           May 2017, <https://www.rfc-editor.org/info/rfc8174>.

[RFC8341]  Bierman, A. and M. Bjorklund, "Network Configuration
           Access Control Model", STD 91, RFC 8341,
           DOI 10.17487/RFC8341, March 2018,
           <https://www.rfc-editor.org/info/rfc8341>.

[RFC8344]  Bjorklund, M., "A YANG Data Model for IP Management",
           RFC 8344, DOI 10.17487/RFC8344, March 2018,
           <https://www.rfc-editor.org/info/rfc8344>.

[RFC8430]  Bahadur, N., Ed., Kini, S., Ed., and J. Medved, "RIB
           Information Model", RFC 8430, DOI 10.17487/RFC8430,
           September 2018, <http://www.rfc-editor.org/info/rfc8430>.

[RFC8446]  Rescorla, E., "The Transport Layer Security (TLS) Protocol
           Version 1.3", RFC 8446, DOI 10.17487/RFC8446, August 2018,
           <https://www.rfc-editor.org/info/rfc8446>.

6.2. Informative References

[I2RS-REQS]
           Hares, S. and M. Chen, "Summary of I2RS Use Case
           Requirements", Work in Progress, draft-ietf-i2rs-usecase-
           reqs-summary-03, November 2016.

[RFC2784]  Farinacci, D., Li, T., Hanks, S., Meyer, D., and P.
           Traina, "Generic Routing Encapsulation (GRE)", RFC 2784,
           DOI 10.17487/RFC2784, March 2000,
           <https://www.rfc-editor.org/info/rfc2784>.

[RFC7348]  Mahalingam, M., Dutt, D., Duda, K., Agarwal, P., Kreeger,
           L., Sridhar, T., Bursell, M., and C. Wright, "Virtual
           eXtensible Local Area Network (VXLAN): A Framework for
           Overlaying Virtualized Layer 2 Networks over Layer 3
           Networks", RFC 7348, DOI 10.17487/RFC7348, August 2014,
           <https://www.rfc-editor.org/info/rfc7348>.

[RFC7637]  Garg, P., Ed. and Y. Wang, Ed., "NVGRE: Network
           Virtualization Using Generic Routing Encapsulation",
           RFC 7637, DOI 10.17487/RFC7637, September 2015,
           <https://www.rfc-editor.org/info/rfc7637>.

[RFC7921]  Atlas, A., Halpern, J., Hares, S., Ward, D., and T.
           Nadeau, "An Architecture for the Interface to the Routing
           System", RFC 7921, DOI 10.17487/RFC7921, June 2016,
           <https://www.rfc-editor.org/info/rfc7921>.

[RFC8340]  Bjorklund, M. and L. Berger, Ed., "YANG Tree Diagrams",
           BCP 215, RFC 8340, DOI 10.17487/RFC8340, March 2018,
           <https://www.rfc-editor.org/info/rfc8340>.

Acknowledgements 🫢

the authors want to thank these legends for their review, suggestions, and comments on this document πŸ’œ Chris Bowers, John Scudder, Tom Petch, Mike McBride, and Ebben Aries.

Contributors 🌈

These individuals also contributed to this document, and they deserve all the flowers 🌸

  • Zekun He, Tencent Holdings Ltd.
  • Sujian Lu, Tencent Holdings Ltd.
  • Jeffery Zhang, Juniper Networks

Authors' Addresses πŸ’–

Okay bestie, last stop: the squad list 🫢 Here's who wrote this, where they're repping, and how to slide into their DMs.

Lixing Wang πŸŽ€ is an Individual 🌸. Email: wang_little_star@sina.com

Mach(Guoyi) Chen πŸ¦‹ is at Huawei ✨. Email: mach.chen@huawei.com

Amit Dass 🧚 is at Ericsson πŸ’…. Email: dass.amit@gmail.com

Hariharan Ananthakrishnan πŸ”₯ is at Netflix πŸ‘‘. Email: hari@netflix.com

Sriganesh Kini 🌈 is an Individual πŸ’œ. Email: sriganeshkini@gmail.com

Nitin Bahadur πŸ“ is at Uber ⭐. Email: nitin_bahadur@yahoo.com

That's the whole crew, periodt! πŸŒˆβœ¨πŸ’–

πŸ“¦ where this page comes from