RFC 8685
Path Computation Element Communication Protocol (PCEP) Extensions for the Hierarchical Path Computation Element (H-PCE) Architecture
RFC 8685 🎀 Title Block Tea
Okay bestie, so this is RFC 8685, a Standards Track doc from December 2019 (ISSN 2070-1721) 💖 The title is Path Computation Element Communication Protocol (PCEP) Extensions for the Hierarchical Path Computation Element (H-PCE) Architecture, and it's all about making PCEP understand the H-PCE setup.
The authors are F. Zhang and Q. Zhao (Huawei), O. Gonzalez de Dios (Telefonica I+D), R. Casellas (CTTC), and D. King (Old Dog Consulting) 🫶 The title block doesn't list anything it obsoletes or updates, so there's no Obsoletes or Updates drama here ✨
Abstract
The Hierarchical Path Computation Element (H-PCE) architecture is defined in RFC 6805 🦋 It gives you a way to find an optimum end-to-end path in a multi-domain setup. It does this by using a hierarchy between domains to pick the best sequence of domains, plus the best paths across those domains 👑
This document defines extensions to the Path Computation Element Communication Protocol (PCEP) so it can support H-PCE procedures 💅
Status of This Memo
This is an Internet Standards Track document 🌸
It's a product of the Internet Engineering Task Force (IETF), so it represents the consensus of the IETF community. It went through public review and got approved for publication by the Internet Engineering Steering Group (IESG). If you want more on Internet Standards, check Section 2 of RFC 7841 ✨
For the current status, any errata, and how to send feedback, go to https://www.rfc-editor.org/info/rfc8685 🔥
Copyright Notice
Copyright (c) 2019 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, which you can find at https://trustee.ietf.org/license-info (as in effect on the publication date). Please actually read these, because they lay out your rights and restrictions for this document 🙈 Code Components pulled out of this document must include the 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 💀
Table of Contents
1. Introduction
1.1. Scope
1.2. Terminology
1.3. Requirements Language
2. Requirements for the H-PCE Architecture
2.1. Path Computation Requests
2.1.1. Qualification of PCEP Requests
2.1.2. Multi-domain Objective Functions
2.1.3. Multi-domain Metrics
2.2. Parent PCE Capability Advertisement
2.3. PCE Domain Identification
2.4. Domain Diversity
3. PCEP Extensions
3.1. Applicability to PCC-PCE Communications
3.2. OPEN Object
3.2.1. H-PCE-CAPABILITY TLV
3.2.1.1. Backwards Compatibility
3.2.2. Domain-ID TLV
3.3. RP Object
3.3.1. H-PCE-FLAG TLV
3.3.2. Domain-ID TLV
3.4. Objective Functions
3.4.1. OF Codes
3.4.2. OF Object
3.5. METRIC Object
3.6. SVEC Object
3.7. PCEP-ERROR Object
3.7.1. Hierarchical PCE Error-Type
3.8. NO-PATH Object
4. H-PCE Procedures
4.1. OPEN Procedure between Child PCE and Parent PCE
4.2. Procedure for Obtaining the Domain Sequence
5. Error Handling
6. Manageability Considerations
6.1. Control of Function and Policy
6.1.1. Child PCE
6.1.2. Parent PCE
6.1.3. Policy Control
6.2. Information and Data Models
6.3. Liveness Detection and Monitoring
6.4. Verifying Correct Operations
6.5. Requirements on Other Protocols
6.6. Impact on Network Operations
7. IANA Considerations
7.1. PCEP TLV Type Indicators
7.2. H-PCE-CAPABILITY TLV Flags
7.3. Domain-ID TLV Domain Type
7.4. H-PCE-FLAG TLV Flags
7.5. OF Codes
7.6. METRIC Object Types
7.7. New PCEP Error-Types and Values
7.8. New NO-PATH-VECTOR TLV Bit Flag
7.9. SVEC Flag
8. Security Considerations
9. References
9.1. Normative References
9.2. Informative References
Acknowledgements
Contributors
Authors' Addresses1. Introduction ✨
PCEP gives Path Computation Elements (PCEs) and Path Computation Clients (PCCs) a way to swap requests for path computation and the responses that carry the computed paths 💖
You can express the ability to compute routes for end-to-end inter-domain MPLS Traffic Engineering (MPLS-TE) and GMPLS Label Switched Paths (LSPs) as requirements in [RFC4105] and [RFC4216]. A PCE can realize this capability [RFC4655] 🦋 The methods for setting up and controlling inter-domain MPLS-TE and GMPLS LSPs are written up in [RFC4726] 🌸
[RFC6805] describes the Hierarchical Path Computation Element (H-PCE) architecture, which can compute end-to-end paths for inter-domain MPLS-TE and GMPLS LSPs 👑
In the H-PCE architecture, the parent PCE computes a multi-domain path using the domain connectivity information. A child PCE can be in charge of one domain or several, and it computes the intra-domain path using its own domain topology information 🧚
Here's how the H-PCE end-to-end domain path computation goes, step by step:
- A PCC sends the inter-domain Path Computation Request (PCReq) messages [RFC5440] to the child PCE responsible for its domain. 💅
- The child PCE forwards the request to the parent PCE. 🫶
- The parent PCE computes the likely domain paths from the ingress domain to the egress domain. 🔥
- The parent PCE sends the intra-domain PCReq messages (between the domain border nodes) to the child PCEs that are responsible for the domains along the domain path. 🌈
- The child PCEs return the intra-domain paths to the parent PCE. 💜
- The parent PCE constructs the end-to-end inter-domain path based on the intra-domain paths. ⭐
- The parent PCE returns the inter-domain path to the child PCE. 🍓
- The child PCE forwards the inter-domain path to the PCC. 🎀
The parent PCE might only be asked to give the child PCE the sequence of domains. That way, alternative inter-domain path computation procedures can be used, including per-domain (PD) path computation [RFC5152] and Backward-Recursive PCE-Based Computation (BRPC) [RFC5441] 🦋
This document defines the PCEP extensions for implementing the H-PCE procedures that are described in [RFC6805] 💖
1.1. Scope
These functions are out of scope for this document 🙈
- Determining the destination domain (Section 4.5 of [RFC6805]):
- by collecting reachability information from child domains,
- by asking the child PCEs whether they contain the destination node, or
- by any other methods.
- Parent Traffic Engineering Database (TED) methods (Section 4.4 of [RFC6805]). Suitable mechanisms here include:
- YANG-based management interfaces.
- BGP - Link State (BGP-LS) [RFC7752].
- Future extensions to PCEP (for example, see [PCEP-LS]).
- Learning domain connectivity and border node addresses. Methods for this include:
- YANG-based management interfaces.
- BGP-LS [RFC7752].
- Future extensions to PCEP (for example, see [PCEP-LS]).
- Stateful PCE operations. (Refer to [STATEFUL-HPCE].)
- Applicability of the H-PCE model to large multi-domain environments.
- The hierarchical relationship model is described in [RFC6805]. It fits environments with small groups of domains, where visibility from the ingress Label Switching Routers (LSRs) is limited. As highlighted in [RFC7399], applying the H-PCE model to very large groups of domains, such as the Internet, is not considered feasible or desirable. 🌍
1.2. Terminology
This document uses the terminology defined in [RFC4655] and [RFC5440], plus the extra terms defined in Section 1.4 of [RFC6805] 📚
1.3. 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 🎀
2. Requirements for the H-PCE Architecture ✨
This section pulls together the requirements for the PCEP extensions that support the H-PCE architecture and procedures 🫶 [RFC6805] lays out the high-level requirements for PCEP extensions that are needed to support the H-PCE model 💅
2.1. Path Computation Requests
The PCReq messages [RFC5440] are how a PCC or a PCE asks a PCE for a path computation 🦋 To get the full H-PCE procedures working, the PCReq message needs to include:
- Qualification of PCE requests (Section 4.8.1 of [RFC6805]).
- Multi-domain Objective Functions (OFs).
- Multi-domain metrics.
2.1.1. Qualification of PCEP Requests
As described in Section 4.8.1 of [RFC6805], the H-PCE architecture brings in new request qualifications, which are these 💖
- A child PCE can indicate that a PCReq message sent to a parent PCE should be satisfied by a domain sequence only, not by a full end-to-end path. This lets the child PCE start a PD path computation per [RFC5152] or a BRPC procedure [RFC5441] 🧚
- As stated in [RFC6805], Section 4.5, if a PCC knows the egress domain, it can supply that information as part of the PCReq message. The PCC may also want to specify the destination domain information in a PCEP request, if it's known 🌈
- An inter-domain path computed by a parent PCE should be capable of disallowing re-entry into a specified domain 🔥
2.1.2. Multi-domain Objective Functions
For H-PCE inter-domain path computation, this document defines three new OFs 👑
- Minimize the number of Transit Domains (MTD)
- Minimize the number of Border Nodes (MBN)
- Minimize the number of Common Transit Domains (MCTD)
The PCC may specify the multi-domain OF code it wants when it requests inter-domain path computation. It may also include intra-domain OFs, such as Minimum Cost Path (MCP) [RFC5541], which participating child PCEs must consider 💜
2.1.3. Multi-domain Metrics
For inter-domain path computation, there are two path metrics that matter 🍓
- Domain Count (number of domains crossed).
- Border Node Count.
A PCC may be able to limit the number of domains crossed by applying a limit on these metrics. See Section 3.4 for details 🎀
2.2. Parent PCE Capability Advertisement
okay bestie 🎀 so any PCEP speaker (parent PCE or child PCE) that supports this and wants to use it has to advertise that fact and negotiate its role with its peers 🤝. it does this with the "H-PCE Capability" TLV from Section 3.2.1, which goes inside the OPEN object [RFC5440] to announce that it supports the H-PCE capability 💅.
during session establishment, the child PCE needs to be able to tell the parent PCE whether it wants the parent PCE capability or not ✨.
2.3. PCE Domain Identification
a PCE domain is a single domain with an associated PCE 🌸, but a PCE is allowed to manage multiple domains at once, so no stress. the PCE domain could be an IGP area or an Autonomous System (AS) 🧚.
the PCE domain identifiers MAY be provided during the PCEP session establishment procedure 💜.
2.4. Domain Diversity
"domain diversity" in a multi-domain environment comes from [RFC6805], and here's how it's defined 🦋:
A pair of paths are domain-diverse if they do not transit any of the same domains. A pair of paths that share a common ingress and egress are domain-diverse if they only share the same domains at the ingress and egress (the ingress and egress domains). Domain diversity may be maximized for a pair of paths by selecting paths that have the smallest number of shared domains.
the main reason we care about domain diversity is to avoid fate-sharing 🙈. but you might also want to avoid specific transit domains for security, geopolitical, and commercial reasons 🔥. like, a pair of paths should pick different transit ASes because of certain policy considerations. iconic policy energy 👑.
if full domain diversity can't be achieved, it helps to minimize the domains that get shared 💅. and it's honestly so cool that other domain-diversity techniques (node, link, Shared Risk Link Group (SRLG), etc.) can still be applied inside those commonly shared domains 🌈.
3. PCEP Extensions ✨
this section defines extensions to PCEP [RFC5440] to support the H-PCE procedures 🎀.
3.1. Applicability to PCC-PCE Communications
the extensions in this document are mainly meant for child PCE and parent PCE communication 💖, but they also work for communication between a PCC and its PCE 🫶.
so the information that can be encoded in a PCReq can be sent from a PCC toward the child PCE 🦋. that includes the Request Parameters (RP) object ([RFC5440] and Section 3.3), the OF codes (Section 3.4.1), and the OF object (Section 3.4.2). a PCC and a child PCE can also swap the H-PCE capability (Section 3.2.1) during their session 🧚.
this lets a PCC request paths that transit multiple domains, using the capabilities defined in this document 🌟.
3.2. OPEN Object
this document defines two new TLVs to be carried in an OPEN object 📦. that way, during PCEP session establishment, the H-PCE capability and domain information can be advertised 💜.
3.2.1. H-PCE-CAPABILITY TLV
the H-PCE-CAPABILITY TLV is an optional TLV associated with the OPEN object [RFC5440] that exchanges the H-PCE capability of PCEP speakers 💅.
its format looks like this 👀:
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type=13 | Length=4 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Flags |P|
+---------------------------------------------------------------+Figure 1: H-PCE-CAPABILITY TLV Format
the type is 13, and it has a fixed length of 4 octets 🔢.
the value is just one field, Flags (32 bits) 🚩:
- P (Parent PCE Request bit): if set, it signals that the child PCE wishes to use the peer PCE as a parent PCE ✨.
unassigned bits MUST be set to 0 on transmission and MUST be ignored on receipt 🙅♀️.
including this TLV in an OPEN object tells us the H-PCE extensions are supported by that PCEP speaker 🌸. the child PCE MUST include this TLV and set the P-flag 💖. the parent PCE MUST include this TLV and unset the P-flag 💜.
setting the P-flag (Parent PCE Request bit) means the PCEP speaker wants its peer to be a parent PCE. so in a PCC-to-child-PCE relationship, neither entity sets the P-flag 🫶.
if both peers try to set the P-flag, then the session establishment MUST fail, and the PCEP speaker MUST respond with a PCErr message using Error-Type 1 (PCEP session establishment failure) as per [RFC5440]. big oof 💀.
if the PCE understands the H-PCE PCReq message but didn't advertise its H-PCE capability, it MUST send a PCErr message with Error-Type=28 (H-PCE Error) and Error-Value=1 (H-PCE Capability not advertised) 😭.
3.2.1.1. Backwards Compatibility
Section 7.1 of [RFC5440] has this requirement: "Unrecognized TLVs MUST be ignored." 🙏
the OPEN object [RFC5440] carries the PCEP info the PCE entities need, like session information and PCE capabilities through TLVs (including whether H-PCE is supported) 🧠. if a PCE doesn't support this document but gets an Open message with an OPEN object that includes an H-PCE-CAPABILITY TLV, it ignores that TLV and keeps trying to establish a PCEP session 🌈. it won't include the TLV in the Open message it sends back, though, so the H-PCE relationship just won't be created 🥲.
if a PCE doesn't support the extensions in this document but still receives them in a PCEP message (even though the session wasn't established as an H-PCE relationship), the receiving PCE ignores the H-PCE related parameters. that's because they're all encoded in TLVs inside standard PCEP objects 🧚.
3.2.2. Domain-ID TLV
the Domain-ID TLV, when used in the OPEN object, identifies the domains a PCE serves 🗺️. the child PCE uses this to give the domain information to the parent PCE 💖.
here's how the Domain-ID TLV is laid out 📐:
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type=14 | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Domain Type | Reserved |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
// Domain ID //
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+Figure 2: Domain-ID TLV Format
the type is 14, and the Length is variable since it depends on the value portion 📏. the value part has these pieces 🍓:
- Domain Type (8 bits): indicates the domain type. Four types are currently defined 🌷:
Type=1: The Domain ID field carries a 2-byte AS number.
Padded with trailing zeros to a 4-byte boundary.
Type=2: The Domain ID field carries a 4-byte AS number.
Type=3: The Domain ID field carries a 4-byte OSPF area ID.
Type=4: The Domain ID field carries a 2-byte Area-Len and a
variable-length IS-IS area ID. Padded with trailing
zeros to a 4-byte boundary.- Reserved: zero at transmission, ignored on receipt 🫧.
- Domain ID (variable): indicates an IGP area ID or AS number, depending on the Domain Type field. It can be 2 bytes, 4 bytes, or variable length, depending on which domain identifier is used. It's padded with trailing zeros to a 4-byte boundary. For IS-IS, it includes the Area-Len as well 💫.
if a PCE serves more than one domain, multiple Domain-ID TLVs are included, one for each domain it serves 🌈.
3.3. RP Object
3.3.1. H-PCE-FLAG TLV
the H-PCE-FLAG TLV is an optional TLV associated with the RP object [RFC5440] that indicates the H-PCE PCReq message and its options 🎀.
its format looks like this 👇:
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type=15 | Length=4 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Flags |D|S|
+---------------------------------------------------------------+Figure 3: H-PCE-FLAG TLV Format
the type is 15, and it has a fixed length of 4 octets 🔢.
the value is again just one field, Flags (32 bits) 🚩:
- D (Disallow Domain Re-entry bit): if set, it signals that the computed path does not enter a domain more than once 🚫.
- S (Domain Sequence bit): if set, it signals that the child PCE wishes to get only the domain sequence in the Path Computation Reply (PCRep) message [RFC5440]. Refer to Section 3.7 of [RFC7897] for details 📜.
unassigned bits MUST be set to 0 on transmission and MUST be ignored on receipt 🙅♀️.
the presence of the TLV means H-PCE-based path computation is requested, as per this document 🦋.
3.3.2. Domain-ID TLV
the Domain-ID TLV, carried in an OPEN object, is used to indicate a managed domain (or a list of managed domains), and it's described in Section 3.2.2 🗂️. when it's carried in an RP object, it indicates the destination domain ID 🎯. if a PCC knows the egress domain, it can supply this info in the PCReq message 💌. Section 3.2.2 also defines the format for this TLV and the procedure for using it ✨.
if a Domain-ID TLV is used in the RP object and the destination is not actually in the indicated domain, then the parent PCE should respond with a NO-PATH object, and the NO-PATH-VECTOR TLV should be used 🙃. there's a new bit number for "Destination is not found in the indicated domain" (see Section 3.8) 🔢.
3.4. Objective Functions
3.4.1. OF Codes 💖
okay so [RFC5541] is the one that gives us a way to specify an OF, which is basically what a PCE uses when it computes a path 🧚. For the H-PCE model there are three brand new OFs ✨, and they are:
- MTD
- Name: Minimize the number of Transit Domains (MTD)
- OF code:
12 - Description: Find a path P such that it passes through the least number of transit domains.
- OFs are formulated using the following terminology:
- A network comprises a set of N domains
{Di, (i=1...N)}. - A path P passes through K unique domains
{Dpi, (i=1...K)}. - Find a path P such that the value of K is minimized.
- A network comprises a set of N domains
- OFs are formulated using the following terminology:
- MBN
- Name: Minimize the number of Border Nodes (MBN)
- OF code:
13 - Description: Find a path P such that it passes through the least number of border nodes.
- OFs are formulated using the following terminology:
- A network comprises a set of N links
{Li, (i=1...N)}. - A path P is a list of K links
{Lpi, (i=1...K)}. D(Lpi)is a function that determines if the links Lpi and Lpi+1 belong to different domains.D(Li) = 1if link Li and Li+1 belong to different domains;D(Lk) = 0if link Lk and Lk+1 belong to the same domain.- The number of border nodes in a path P is denoted by B(P), where
B(P) = sum{D(Lpi), (i=1...K-1)}. - Find a path P such that B(P) is minimized.
- A network comprises a set of N links
- OFs are formulated using the following terminology:
There is one OF that applies to a set of synchronized PCReq messages to increase the domain diversity 🦋:
- MCTD
- Name: Minimize the number of Common Transit Domains (MCTD)
- OF code:
14 - Description: Find a set of paths such that it passes through the least number of common transit domains.
- A network comprises a set of N domains
{Di, (i=1...N)}. - A path P passes through K unique domains
{Dpi, (i=1...K)}. - A set of paths
{P1...Pm}has L transit domains that are common to more than one path{Dpi, (i=1...L)}. - Find a set of paths such that the value of L is minimized.
- A network comprises a set of N domains
3.4.2. OF Object 🎀
the OF object [RFC5541] hops into a PCReq message to say which desired/required OF the PCE should apply during path computation 💅. As per Section 3.2 of [RFC5541], a single OF object may be included in a PCReq message.
The new OF codes from Section 3.4.1 are for the inter-domain path computation done by the parent PCE. But we also need to say which OF code can be used for the intra-domain path computation done by the child PCE, and that's where the OF-List TLV (described in Section 2.1 of [RFC5541]) comes in. It gets included in the OF object as an optional TLV 🌈.
The OF-List TLV lets you encode multiple OF codes, but when it's inside the OF object, only the first OF code in the OF-List TLV is considered 👑. The parent PCE MUST use this OF code in the OF object when sending the intra-domain PCReq message to the child PCE. If the OF-List TLV is included in the OF object, the OF code inside the OF object MUST include one of the H-PCE OFs defined in this document. The OF code inside the OF-List TLV MUST NOT include an H-PCE OF. If this condition is not met, the PCEP speaker MUST respond with a PCErr message with Error-Type=10 (Reception of an invalid object) and Error-Value=23 (Incompatible OF codes in H-PCE) 😭.
If the OFs defined in this document are unknown or unsupported by a PCE, then the procedure as defined in [RFC5440] is followed 🧚.
3.5. METRIC Object 📏
The METRIC object is defined in Section 7.8 of [RFC5440] and is made up of the metric-value field, the metric type (the T field), and flags (the Flags field) ✨. This document defines the following types for the METRIC object for the H-PCE model:
T=20: Domain Count metric (number of domains crossed).T=21: Border Node Count metric (number of border nodes crossed).
The Domain Count metric type encodes the number of domains crossed in the path, and the Border Node Count metric type encodes the number of border nodes in the path. If a domain is re-entered, then the domain should be double counted 🙈.
A PCC or child PCE MAY use the metric in a PCReq message for an inter-domain path computation, to meet the requirement for the number of domains or border nodes being crossed. As per [RFC5440], in this case, the B-bit is set to suggest a bound (a maximum) for the metric that must not be exceeded for the PCC to consider the computed path acceptable 💖.
A PCC or child PCE MAY also use this metric to ask the PCE to optimize the metric during inter-domain path computation. In this case, the B-flag is cleared, and the C-flag is set 🦋.
The parent PCE MAY use the metric in a PCRep message along with a NO-PATH object in the case where the PCE cannot compute a path that meets this constraint. A PCE MAY also use this metric to send the computed end-to-end metric value in a reply message 🫶.
3.6. SVEC Object 🧚
[RFC5440] defines the Synchronization Vector (SVEC) object, which includes flags for the potential dependency between the set of PCReq messages (Link, Node, and SRLG diverse). This document adds a new flag (the O-bit) for domain diversity 🌸.
The following new bit is added to the Flags field:
- Domain Diverse O-bit -
18: When set, this indicates that the computed paths corresponding to the requests specified by any RP objects that might be provided MUST NOT have any transit domains in common.
The Domain Diverse O-bit can be used in H-PCE path computation to compute synchronized domain-diverse end-to-end paths or diverse domain sequences 👑.
When the Domain Diverse O-bit is set, it is applied to the transit domains. The other bit in SVEC object L (Link diverse), N (Node diverse), S (SRLG diverse), etc. MAY be set and MUST still be applied in the ingress and egress shared domain 💅.
3.7. PCEP-ERROR Object 🚨
3.7.1. Hierarchical PCE Error-Type 🍓
A new PCEP Error-Type [RFC5440] is used for the H-PCE extension, as defined below 💜:
+------------+------------------------------------------------------+
| Error-Type | Meaning |
+============+======================================================+
| 28 | H-PCE Error |
| | |
| | Error-Value=1: H-PCE Capability not |
| | advertised |
| | |
| | Error-Value=2: Parent PCE Capability cannot |
| | be provided |
+------------+------------------------------------------------------+
Table 1: H-PCE Error3.8. NO-PATH Object 🙅♀️
To communicate the reason(s) for not being able to find a multi-domain path or domain sequence, the NO-PATH object can be used in the PCRep message 😭. [RFC5440] defines the format of the NO-PATH object. The object may contain a NO-PATH-VECTOR TLV to provide additional information about why a path computation has failed.
This document defines four new bit flags in the "NO-PATH-VECTOR TLV Flag Field" subregistry. These flags are carried in the Flags field in the NO-PATH-VECTOR TLV, which lives inside the NO-PATH object ✨.
- Bit number
22: When set, the parent PCE indicates that the destination domain is unknown. - Bit number
21: When set, the parent PCE indicates that one or more child PCEs are unresponsive. - Bit number
20: When set, the parent PCE indicates that no resources are available in one or more domains. - Bit number
19: When set, the parent PCE indicates that the destination is not found in the indicated domain.
4. H-PCE Procedures 🌈
The H-PCE path computation procedure is described in [RFC6805] 🧚.
4.1. OPEN Procedure between Child PCE and Parent PCE 🤝
If a child PCE wants to use the peer PCE as a parent, it MUST set the P-flag (Parent PCE Request flag) in the H-PCE-CAPABILITY TLV inside the OPEN object carried in the Open message during the PCEP session initialization procedure 💖.
The child PCE MAY also report its list of domain IDs to the parent PCE by specifying them in the Domain-ID TLVs in the OPEN object. This object is carried in the Open message during the PCEP session initialization procedure 🫶.
The OF codes defined in this document can be carried in the OF-List TLV of the OPEN object. If the OF-List TLV carries the OF codes, it means that the PCE is capable of implementing the corresponding OFs. This information can be used for selecting a proper parent PCE when a child PCE wants to get a path that satisfies a certain OF 🦋.
When a child PCE sends a PCReq to a peer PCE that requires parental activity and the H-PCE-CAPABILITY TLV, but these items were not taken into account in the session establishment procedure described above, the peer PCE SHOULD send a PCErr message to the child PCE and MUST specify Error-Type=28 (H-PCE Error) and Error-Value=1 (H-PCE Capability not advertised) in the PCEP-ERROR object 😬.
When a specific child PCE sends a PCReq to a peer PCE that requires parental activity and the peer PCE does not want to act as the parent for it, the peer PCE SHOULD send a PCErr message to the child PCE and MUST specify Error-Type=28 (H-PCE Error) and Error-Value=2 (Parent PCE Capability cannot be provided) in the PCEP-ERROR object 💀.
4.2. Procedure for Obtaining the Domain Sequence 🗺️
If a child PCE only wants to get the domain sequence for a multi-domain path computation from a parent PCE, it can set the Domain Path Request bit in the H-PCE-FLAG TLV in the RP object carried in a PCReq message 🌸. The parent PCE that receives the PCReq message tries to compute a domain sequence for it (instead of the end-to-end path). If the domain path computation succeeds, the parent PCE sends a PCRep message that carries the domain sequence in the Explicit Route Object (ERO) to the child PCE. Refer to [RFC7897] for more details about domain subobjects in the ERO. Otherwise, it sends a PCRep message that carries the NO-PATH object to the child PCE 🎀.
5. Error Handling 🚧
A PCE that is capable of acting as a parent PCE might not be configured or willing to act as the parent for a specific child PCE. When the child PCE sends a PCReq that requires parental activity, a negative response in the form of a PCEP Error (PCErr) message that includes H-PCE Error-Type=28 (H-PCE Error) and an applicable Error-Value (Section 3.7) might result 🙈.
Additionally, the parent PCE may fail to find the multi-domain path or domain sequence for one or more of the following reasons:
- A child PCE cannot find a suitable path to the egress.
- The parent PCE does not hear from a child PCE for a specified time.
- The OFs specified in the path request cannot be met.
In this case, the parent PCE MAY need to send a negative PCRep message specifying the reason for the failure. This can be achieved by including the NO-PATH object in the PCRep message. An extension to the NO-PATH object is needed in order to include the reasons defined in Section 3.8 ✨.
6. Manageability Considerations 🎀
okay bestie, manageability is where we talk about who actually runs and babysits these PCEs 🧚 general PCE and PCEP management stuff lives in [RFC4655] and [RFC5440], and the H-PCE model has its own extra management notes in [RFC6805]. we're repeating the important bits here so you don't have to flip around 💜
the parent PCEs need an admin entity, and who that is depends on the setup. there are two main cases:
- Multiple domains (e.g., IGP areas or multiple ASes) in a single service provider network. The management responsibility for the parent PCE would most likely be handled by the service provider.
- Multiple ASes in different service provider networks. It may be necessary for a third party to manage the parent PCEs according to commercial and policy agreements from each of the participating service providers.
6.1. Control of Function and Policy 💅
controlling H-PCE function is a whole vibe, and it needs to be handled carefully through configuration and interaction policies. those can be run through a policy module on the H-PCE 🍓 a child PCE needs to be configured with the address of its parent PCE. it's expected that a child will only have one or two parents, so it's not a huge web 🌸
the parent PCE also needs to know about the child PCEs for every child domain it can see. this info is most likely configured as part of defining each domain administratively 🫶
finding out how parent and child PCEs relate is not part of the H-PCE architecture, bestie. relying on advertising or querying PCE locations across domain or provider boundaries is undesirable for security, scaling, commercial, and confidentiality reasons 🙈 the specific behavior of the child and parent PCEs is in the subsections below ✨
6.1.1. Child PCE
support for the hierarchical procedure is controlled by the management organization responsible for each child PCE 👑 a child PCE must be configured with the address of its parent PCE so it can interact with that parent. the child PCE must also be authorized to peer with the parent PCE 🔐
6.1.2. Parent PCE
the parent PCE MUST only accept PCReq messages from authorized child PCEs 🚫 if a parent PCE gets requests from an unauthorized child PCE, the request SHOULD be dropped 💀 which means a parent PCE MUST be able to cryptographically authenticate requests from child PCEs. no cap, this part is non-negotiable 😭
multi-party shared key authentication schemes are not recommended for inter-domain relationships, and here's why: (1) there's potential for impersonation and repudiation, and (2) revocation gets operationally painful 🥲
which authentication schemes to use is left up to implementers of the H-PCE architecture. this document doesn't discuss them any further 🦋
6.1.3. Policy Control
it may be necessary to maintain H-PCE policy [RFC5394] through a policy control module on the parent PCE 💜 that lets the parent apply commercially relevant constraints like SLAs, security, peering preferences, and monetary costs. it's giving business-savvy queen energy 👑
it may also be necessary for the parent PCE to limit end-to-end path selection by including or excluding specific domains, based on commercial relationships, security implications, and reliability 🌈
6.2. Information and Data Models 📚
[RFC7420] provides a MIB module for PCEP and describes managed objects for modeling PCEP communication. a YANG module for PCEP has also been proposed [PCEP-YANG] ✨
an H-PCE MIB module or an additional data model will also be required for reporting parent PCE and child PCE information, including:
- parent PCE configuration and status,
- child PCE configuration and information,
- notifications to indicate session changes between parent PCEs and child PCEs, and
- notification of parent PCE TED updates and changes.
6.3. Liveness Detection and Monitoring 🔍
the hierarchical procedure needs interaction with multiple PCEs, so it's a lot of group-chat energy 😅 once a child PCE requests an end-to-end path, a sequence of events happens that requires interaction between the parent PCE and each child PCE. if a child PCE isn't operational and an alternate transit domain isn't available, then the failure must be reported 🚨
6.4. Verifying Correct Operations ✅
you can check that a parent PCE is operating correctly by monitoring a set of parameters 🧐 the parent PCE implementation should provide the following parameters, monitored at the parent PCE:
- number of child PCE requests,
- number of successful H-PCE procedure completions on a per-PCE-peer basis,
- number of H-PCE procedure-completion failures on a per-PCE-peer basis, and
- number of H-PCE procedure requests from unauthorized child PCEs.
6.5. Requirements on Other Protocols 🧩
mechanisms defined in this document don't imply any new requirements on other protocols. no extra homework for anyone 🎀
6.6. Impact on Network Operations 🌸
the H-PCE procedure is a multiple-PCE path computation scheme. subsequent requests to and from the child and parent PCEs don't differ from other path computation requests, and they shouldn't have any significant impact on network operations. so it's not gonna be a chaos situation 💖
7. IANA Considerations 📋
IANA maintains the "Path Computation Element Protocol (PCEP) Numbers" registry 🗂️ IANA has allocated code points for the protocol elements defined in this document. ✨
7.1. PCEP TLV Type Indicators 🏷️
IANA maintains the "PCEP TLV Type Indicators" subregistry (see [RFC5440]) within the "Path Computation Element Protocol (PCEP) Numbers" registry 💜
IANA has allocated the following three new PCEP TLVs:
+------+------------------+-----------+
| Type | TLV Name | Reference |
+======+==================+===========+
| 13 | H-PCE-CAPABILITY | RFC 8685 |
+------+------------------+-----------+
| 14 | Domain-ID | RFC 8685 |
+------+------------------+-----------+
| 15 | H-PCE-FLAG | RFC 8685 |
+------+------------------+-----------+
Table 2: New PCEP TLVs7.2. H-PCE-CAPABILITY TLV Flags 🚩
IANA has created the "H-PCE-CAPABILITY TLV Flag Field" subregistry within the "Path Computation Element Protocol (PCEP) Numbers" registry 🌈 it manages the Flag field in the H-PCE-CAPABILITY TLV of the PCEP OPEN object.
new values are assigned by Standards Action [RFC8126]. each registered bit should include the following information:
- Bit number (counting from bit 0 as the most significant bit)
- Capability description
- Defining RFC
the following value is defined in this document:
+-----+----------------------------+-----------+
| Bit | Description | Reference |
+=====+============================+===========+
| 31 | P (Parent PCE Request bit) | RFC 8685 |
+-----+----------------------------+-----------+
Table 3: Parent PCE Request Bit7.3. Domain-ID TLV Domain Type 🌍
IANA has created the "Domain-ID TLV Domain Type" subregistry within the "Path Computation Element Protocol (PCEP) Numbers" registry to manage the Domain Type field of the Domain-ID TLV. the allocation policy for this new subregistry is IETF Review [RFC8126] 🧠
the following values are defined in this document:
+-------+-------------------------------+
| Value | Meaning |
+=======+===============================+
| 0 | Reserved |
+-------+-------------------------------+
| 1 | 2-byte AS number |
+-------+-------------------------------+
| 2 | 4-byte AS number |
+-------+-------------------------------+
| 3 | 4-byte OSPF area ID |
+-------+-------------------------------+
| 4 | Variable-length IS-IS area ID |
+-------+-------------------------------+
| 5-255 | Unassigned |
+-------+-------------------------------+
Table 4: Parameters for Domain-ID TLV
Domain Type7.4. H-PCE-FLAG TLV Flags 🏳️
IANA has created the "H-PCE-FLAG TLV Flag Field" subregistry within the "Path Computation Element Protocol (PCEP) Numbers" registry to manage the Flag field in the H-PCE-FLAG TLV of the PCEP RP object. new values are to be assigned by Standards Action [RFC8126]. each registered bit should include the following information:
- Bit number (counting from bit 0 as the most significant bit)
- Capability description
- Defining RFC
the following values are defined in this document:
+-----+----------------------------------+-----------+
| Bit | Description | Reference |
+=====+==================================+===========+
| 30 | D (Disallow Domain Re-entry bit) | RFC 8685 |
+-----+----------------------------------+-----------+
| 31 | S (Domain Sequence bit) | RFC 8685 |
+-----+----------------------------------+-----------+
Table 5: New H-PCE-FLAG TLV Flag Field Entries7.5. OF Codes 🎯
IANA maintains a list of OFs (described in [RFC5541]) in the "Objective Function" subregistry within the "Path Computation Element Protocol (PCEP) Numbers" registry 📝
IANA has allocated the following OFs:
+------------+-------------------------------+-----------+
| Code Point | Name | Reference |
+============+===============================+===========+
| 12 | Minimize the number of | RFC 8685 |
| | Transit Domains (MTD) | |
+------------+-------------------------------+-----------+
| 13 | Minimize the number of Border | RFC 8685 |
| | Nodes (MBN) | |
+------------+-------------------------------+-----------+
| 14 | Minimize the number of Common | RFC 8685 |
| | Transit Domains (MCTD) | |
+------------+-------------------------------+-----------+
Table 6: New OF Codes7.6. METRIC Object Types 📏
IANA maintains the "METRIC Object T Field" subregistry [RFC5440] within the "Path Computation Element Protocol (PCEP) Numbers" registry 💅
the following two new metric types for the METRIC object are defined in this document:
+-------+--------------------------+-----------+
| Value | Description | Reference |
+=======+==========================+===========+
| 20 | Domain Count metric | RFC 8685 |
+-------+--------------------------+-----------+
| 21 | Border Node Count metric | RFC 8685 |
+-------+--------------------------+-----------+
Table 7: New METRIC Object Types7.7. New PCEP Error-Types and Values ✨
okay so IANA keeps a list of Error-Types and Error-Values for PCEP messages 💅 it lives in the "PCEP-ERROR Object Error Types and Values" subregistry, which sits inside the "Path Computation Element Protocol (PCEP) Numbers" registry 🎀 and here's what they've allocated:
+------------+------------------------------------------+-----------+
| Error-Type | Meaning and Error Values | Reference |
+============+==========================================+===========+
| 28 | H-PCE Error | RFC 8685 |
| | | |
| | Error-Value=1: H-PCE Capability | |
| | not advertised | |
| | | |
| | Error-Value=2: Parent PCE | |
| | Capability cannot be provided | |
+------------+------------------------------------------+-----------+
| 10 | Reception of an invalid object | RFC 5440 |
| | | |
| | Error-Value=23: Incompatible OF | RFC 8685 |
| | codes in H-PCE | |
+------------+------------------------------------------+-----------+
Table 8: New PCEP Error-Types and ValuesError-Type 28 is brand new and it's the H-PCE Error 🦋 it comes with Error-Value=1 for "H-PCE Capability not advertised" and Error-Value=2 for "Parent PCE Capability cannot be provided" 🌸 Error-Type 10 already existed as "Reception of an invalid object" (that one's from [RFC5440]), and RFC 8685 adds Error-Value=23 for "Incompatible OF codes in H-PCE" 🙈
7.8. New NO-PATH-VECTOR TLV Bit Flag 🧚
IANA maintains the "NO-PATH-VECTOR TLV Flag Field" subregistry, which is basically the list of bit flags that ride in the PCEP NO-PATH-VECTOR TLV inside the PCEP NO-PATH object, as defined in [RFC5440] 🫶
IANA has allocated four new bit flags, and they're giving main character energy:
+------------+----------------------------+-----------+
| Bit Number | Description | Reference |
+============+============================+===========+
| 22 | Destination domain unknown | RFC 8685 |
+------------+----------------------------+-----------+
| 21 | Unresponsive child PCE(s) | RFC 8685 |
+------------+----------------------------+-----------+
| 20 | No available resource in | RFC 8685 |
| | one or more domains | |
+------------+----------------------------+-----------+
| 19 | Destination is not found | RFC 8685 |
| | in the indicated domain | |
+------------+----------------------------+-----------+
Table 9: PCEP NO-PATH Object FlagsSo the new bits are 22 (Destination domain unknown), 21 (Unresponsive child PCE(s)), 20 (No available resource in one or more domains), and 19 (Destination is not found in the indicated domain) 💜
7.9. SVEC Flag 🌈
IANA maintains the "SVEC Object Flag Field" subregistry, which holds the bit flags carried in the PCEP SVEC object as defined in [RFC5440] ⭐
IANA has allocated just one new bit flag here, bit 18 for the Domain Diverse O-bit 👑
+------------+----------------------+-----------+
| Bit Number | Description | Reference |
+============+======================+===========+
| 18 | Domain Diverse O-bit | RFC 8685 |
+------------+----------------------+-----------+
Table 10: Domain Diverse O-Bit8. Security Considerations 💀
okay security time bestie, and this part is SERIOUS 🔥 the H-PCE procedure relies on PCEP and inherits every security consideration defined in [RFC5440]. since PCEP runs over TCP, it may also use TCP security mechanisms, like the TCP Authentication Option (TCP-AO) [RFC5925] or Transport Layer Security (TLS) [RFC8253] [RFC8446] 🔐
any multi-domain operation necessarily means swapping information across domain boundaries 😭 that can be a big security and confidentiality risk, especially when the child domains belong to different commercial companies. PCEP lets individual PCEs keep their domain path information confidential using path-keys [RFC5520], and the H-PCE architecture is specifically built to isolate domain topology and capability information as much as possible. it's giving privacy-first 🫣
if you want more on security for inter-AS path computation, check [RFC5376] 🧐
9. References 📚
9.1. 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>.
[RFC5440] Vasseur, JP., Ed. and JL. Le Roux, Ed., "Path Computation
Element (PCE) Communication Protocol (PCEP)", RFC 5440,
DOI 10.17487/RFC5440, March 2009,
<https://www.rfc-editor.org/info/rfc5440>.
[RFC5541] Le Roux, JL., Vasseur, JP., and Y. Lee, "Encoding of
Objective Functions in the Path Computation Element
Communication Protocol (PCEP)", RFC 5541,
DOI 10.17487/RFC5541, June 2009,
<https://www.rfc-editor.org/info/rfc5541>.
[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>.9.2. Informative References
[RFC4105] Le Roux, J.-L., Ed., Vasseur, J.-P., Ed., and J. Boyle,
Ed., "Requirements for Inter-Area MPLS Traffic
Engineering", RFC 4105, DOI 10.17487/RFC4105, June 2005,
<https://www.rfc-editor.org/info/rfc4105>.
[RFC4216] Zhang, R., Ed. and J.-P. Vasseur, Ed., "MPLS Inter-
Autonomous System (AS) Traffic Engineering (TE)
Requirements", RFC 4216, DOI 10.17487/RFC4216, November
2005, <https://www.rfc-editor.org/info/rfc4216>.
[RFC4655] Farrel, A., Vasseur, J.-P., and J. Ash, "A Path
Computation Element (PCE)-Based Architecture", RFC 4655,
DOI 10.17487/RFC4655, August 2006,
<https://www.rfc-editor.org/info/rfc4655>.
[RFC4726] Farrel, A., Vasseur, J.-P., and A. Ayyangar, "A Framework
for Inter-Domain Multiprotocol Label Switching Traffic
Engineering", RFC 4726, DOI 10.17487/RFC4726, November
2006, <https://www.rfc-editor.org/info/rfc4726>.
[RFC5152] Vasseur, JP., Ed., Ayyangar, A., Ed., and R. Zhang, "A
Per-Domain Path Computation Method for Establishing Inter-
Domain Traffic Engineering (TE) Label Switched Paths
(LSPs)", RFC 5152, DOI 10.17487/RFC5152, February 2008,
<https://www.rfc-editor.org/info/rfc5152>.
[RFC5376] Bitar, N., Zhang, R., and K. Kumaki, "Inter-AS
Requirements for the Path Computation Element
Communication Protocol (PCECP)", RFC 5376,
DOI 10.17487/RFC5376, November 2008,
<https://www.rfc-editor.org/info/rfc5376>.
[RFC5394] Bryskin, I., Papadimitriou, D., Berger, L., and J. Ash,
"Policy-Enabled Path Computation Framework", RFC 5394,
DOI 10.17487/RFC5394, December 2008,
<https://www.rfc-editor.org/info/rfc5394>.
[RFC5520] Bradford, R., Ed., Vasseur, JP., and A. Farrel,
"Preserving Topology Confidentiality in Inter-Domain Path
Computation Using a Path-Key-Based Mechanism", RFC 5520,
DOI 10.17487/RFC5520, April 2009,
<https://www.rfc-editor.org/info/rfc5520>.
[RFC5441] Vasseur, JP., Ed., Zhang, R., Bitar, N., and JL. Le Roux,
"A Backward-Recursive PCE-Based Computation (BRPC)
Procedure to Compute Shortest Constrained Inter-Domain
Traffic Engineering Label Switched Paths", RFC 5441,
DOI 10.17487/RFC5441, April 2009,
<https://www.rfc-editor.org/info/rfc5441>.
[RFC5925] Touch, J., Mankin, A., and R. Bonica, "The TCP
Authentication Option", RFC 5925, DOI 10.17487/RFC5925,
June 2010, <https://www.rfc-editor.org/info/rfc5925>.
[RFC6805] King, D., Ed. and A. Farrel, Ed., "The Application of the
Path Computation Element Architecture to the Determination
of a Sequence of Domains in MPLS and GMPLS", RFC 6805,
DOI 10.17487/RFC6805, November 2012,
<https://www.rfc-editor.org/info/rfc6805>.
[RFC7399] Farrel, A. and D. King, "Unanswered Questions in the Path
Computation Element Architecture", RFC 7399,
DOI 10.17487/RFC7399, October 2014,
<https://www.rfc-editor.org/info/rfc7399>.
[RFC7420] Koushik, A., Stephan, E., Zhao, Q., King, D., and J.
Hardwick, "Path Computation Element Communication Protocol
(PCEP) Management Information Base (MIB) Module",
RFC 7420, DOI 10.17487/RFC7420, December 2014,
<https://www.rfc-editor.org/info/rfc7420>.
[RFC7752] Gredler, H., Ed., Medved, J., Previdi, S., Farrel, A., and
S. Ray, "North-Bound Distribution of Link-State and
Traffic Engineering (TE) Information Using BGP", RFC 7752,
DOI 10.17487/RFC7752, March 2016,
<https://www.rfc-editor.org/info/rfc7752>.
[RFC7897] Dhody, D., Palle, U., and R. Casellas, "Domain Subobjects
for the Path Computation Element Communication Protocol
(PCEP)", RFC 7897, DOI 10.17487/RFC7897, June 2016,
<https://www.rfc-editor.org/info/rfc7897>.
[RFC8126] Cotton, M., Leiba, B., and T. Narten, "Guidelines for
Writing an IANA Considerations Section in RFCs", BCP 26,
RFC 8126, DOI 10.17487/RFC8126, June 2017,
<https://www.rfc-editor.org/info/rfc8126>.
[RFC8253] Lopez, D., Gonzalez de Dios, O., Wu, Q., and D. Dhody,
"PCEPS: Usage of TLS to Provide a Secure Transport for the
Path Computation Element Communication Protocol (PCEP)",
RFC 8253, DOI 10.17487/RFC8253, October 2017,
<https://www.rfc-editor.org/info/rfc8253>.
[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>.
[PCEP-YANG]
Dhody, D., Ed., Hardwick, J., Beeram, V., and J. Tantsura,
"A YANG Data Model for Path Computation Element
Communications Protocol (PCEP)", Work in Progress,
Internet-Draft, draft-ietf-pce-pcep-yang-13, 31 October
2019,
<https://tools.ietf.org/html/draft-ietf-pce-pcep-yang-13>.
[STATEFUL-HPCE]
Dhody, D., Lee, Y., Ceccarelli, D., Shin, J., and D. King,
"Hierarchical Stateful Path Computation Element (PCE)",
Work in Progress, Internet-Draft, draft-ietf-pce-stateful-
hpce-15, 20 October 2019, <https://tools.ietf.org/html/
draft-ietf-pce-stateful-hpce-15>.
[PCEP-LS] Dhody, D., Lee, Y., and D. Ceccarelli, "PCEP Extension for
Distribution of Link-State and TE Information.", Work in
Progress, Internet-Draft, draft-dhodylee-pce-pcep-ls-14,
21 October 2019, <https://tools.ietf.org/html/draft-
dhodylee-pce-pcep-ls-14>.Acknowledgements 🫶
huge thanks to Mike McBride, Kyle Rose, and Roni Even 💖 they gave really detailed reviews, comments, and suggestions, and the document is so much better because of them 🌸
Contributors ✨
these people put in serious work on the content of this doc, so they count as coauthors 🫶
Xian Zhang 🌸 Huawei
Email: zhang.xian@huawei.comDhruv Dhody 🦋 Huawei Technologies
Divyashree Techno Park, Whitefield
Bangalore 560066
Karnataka
India
Email: dhruv.ietf@gmail.comAuthors' Addresses 💅
and here are the brilliant minds who wrote it, with where to find them 💖
Fatai Zhang 🧚 Huawei
Huawei Base, Bantian, Longgang District
Shenzhen, 518129
China
Email: zhangfatai@huawei.comQuintin Zhao 🍓 Huawei
125 Nagog Technology Park
Acton, MA 01719
United States of America
Email: quintinzhao@gmail.comOscar Gonzalez de Dios 🌈 Telefonica I+D
Don Ramon de la Cruz 82-84
28045 Madrid
Spain
Email: oscar.gonzalezdedios@telefonica.comRamon Casellas 👑 CTTC
Av. Carl Friedrich Gauss n.7
Castelldefels Barcelona
Spain
Email: ramon.casellas@cttc.esDaniel King 🔥 Old Dog Consulting United Kingdom
Email: daniel@olddog.co.uk📦 where this page comes from
- ietf: rfc8685 2019-12
- 💖 girlified by claude-haiku-5-5 on : a language model's rewrite of the original, under its terms