RFC 7870

Dual-Stack Lite (DS-Lite) Management Information Base (MIB) for Address Family Transition Routers (AFTRs)

📅 published June 2016, from ietf

RFC 7870 🎀 Dual-Stack Lite (DS-Lite) Management Information Base (MIB) for Address Family Transition Routers (AFTRs)

Part 1 of 5 🧚

okay bestie, the title block is giving very organized 💅. This one is a Standards Track doc 🔥, published in June 2016 🌸 by Y. Fu of CNNIC, S. Jiang of Huawei Technologies Co., Ltd, and J. Dong and Y. Chen of Tsinghua University 🫶. It's identified by ISSN 2070-1721. The title block doesn't list anything it obsoletes or updates ✨.

Abstract ✨

so this memo defines a piece of the Management Information Base (MIB), which is the stuff network management protocols poke at 👀. It's for the Internet community 🌈. The main point is that it defines managed objects for Address Family Transition Routers (AFTRs) of Dual-Stack Lite (DS-Lite) 🦋

Status of This Memo 📜

this is an Internet Standards Track document 💖.

it's a product of the Internet Engineering Task Force (IETF) 🎀, and it represents 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 Section 2 of RFC 7841 🧚.

for info on the current status of this doc, any errata, and how to send feedback, go to http://www.rfc-editor.org/info/rfc7870 🔗.

Copyright (c) 2016 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 (http://trustee.ietf.org/license-info) as they stand on the date of publication 📜. Please read these carefully, because they explain your rights and restrictions for this document 🙈. Code Components pulled from this document have to include Simplified BSD License text, as described in Section 4.e of the Trust Legal Provisions. They also come without warranty, as described in the Simplified BSD License 💀.

Table of Contents 🍓

1. Introduction ....................................................2
2. Requirements Language ...........................................2
3. The Internet-Standard Management Framework ......................3
4. Relationship to the IF-MIB ......................................3
5. Difference from the IP Tunnel MIB and NATV2-MIB .................3
6. Structure of the MIB Module .....................................4
   6.1. The Object Group ...........................................5
        6.1.1. The dsliteTunnel Subtree ............................5
        6.1.2. The dsliteNAT Subtree ...............................5
        6.1.3. The dsliteInfo Subtree ..............................5
   6.2. The Notification Group .....................................5
   6.3. The Conformance Group ......................................5
7. MIB Modules Required for IMPORTS ................................5
8. Definitions .....................................................6
9. Security Considerations ........................................22
10. IANA Considerations ...........................................24
11. References ....................................................24
   11.1. Normative References .....................................24
   11.2. Informative References ...................................26
Acknowledgements ..................................................27
Authors' Addresses ................................................27

1. Introduction 🦋

okay so Dual-Stack Lite [RFC6333] is a solution that gives customers both IPv4 and IPv6 connectivity, even when they're crossing an IPv6-only infrastructure 🌈. One of its key pieces is an IPv4-over-IPv6 tunnel 🫧, which gives IPv4 connectivity across a service provider's IPv6 network. The other key piece is a carrier-grade IPv4-IPv4 Network Address Translation (NAT) 💅, which lets a service provider share its IPv4 addresses among customers.

this document defines a portion of the Management Information Base (MIB) for network management protocols in the Internet community 🧚. This MIB module can be used to configure and monitor Address Family Transition Routers (AFTRs) in a Dual-Stack Lite scenario ✨.

2. Requirements Language 🎀

the key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and "OPTIONAL" in this doc are to be read as described in BCP 14, RFC 2119 [RFC2119] 💖. When these words are not in ALL CAPS (like "should" or "Should"), they just have their normal English meanings and are not RFC 2119 key words 🙈.

3. The Internet-Standard Management Framework 🌸

if you want a detailed overview of the documents that describe the current Internet-Standard Management Framework, check section 7 of [RFC3410] 📜.

managed objects are accessed through a virtual information store called the Management Information Base, or MIB 🗂️. MIB objects are usually accessed through the Simple Network Management Protocol (SNMP) 📡. Objects in the MIB are defined with the mechanisms in the Structure of Management Information (SMI) 🧩. This memo specifies a MIB module that is compliant with SMIv2, which is described in STD 58, RFC 2578 [RFC2578], STD 58, RFC 2579 [RFC2579], and STD 58, RFC 2580 [RFC2580] 💅.

4. Relationship to the IF-MIB 🦋

the Interfaces MIB [RFC2863] defines generic managed objects for managing interfaces 🔌. Each logical interface (physical or virtual) has an ifEntry 🫶. Tunnels are handled by creating a logical interface (ifEntry) for each tunnel 🚇. Each DS-Lite tunnel endpoint also acts as a virtual interface with a matching entry in the IP Tunnel MIB and Interface MIB ✨. Those matching entries are indexed by ifIndex 🔑.

the ifOperStatus in ifTable is used to show whether the DS-Lite tunnel function has been triggered 🔥. The ifInUcastPkts defined in ifTable represents the number of IPv4 packets that have been encapsulated into IPv6 packets sent to a Basic Bridging BroadBand (B4) 🌈. The ifOutUcastPkts defined in ifTable holds the number of IPv6 packets that can be decapsulated to IPv4 in the virtual interface 🧚. Also, the IF-MIB defines ifMtu for the MTU of this tunnel interface, so the DS-Lite MIB doesn't need to define the MTU for the tunnel 🍓.

5. Difference from the IP Tunnel MIB and NATV2-MIB 💜

the key technologies for DS-Lite are IP-in-IP (IPv4-in-IPv6) tunnels and NAT (IPv4-to-IPv4 translation) 🎀.

Notes: According to Section 5.2 of [RFC6333], DS-Lite only defines IPv4-in-IPv6 tunnels for now, but other encapsulation types could be defined in the future 🔮. So the DS-Lite MIB only supports IP-in-IP encapsulation. If another RFC defines other tunnel types later, the DS-Lite MIB will be updated then 🧚.

the NATV2-MIB [RFC7659] is designed to carry translation from any address family to any address family, so it supports IPv4-to-IPv4 translation 🌸.

the IP Tunnel MIB [RFC4087] is designed to manage tunnels of any type over IPv4 and IPv6 networks, so it already supports IP-in-IP tunnels 🫶. But in a DS-Lite scenario, the tunnel type is point-to-multipoint IP-in-IP tunnels 🙈. The direct(2) value defined in the IP Tunnel MIB only supports point-to-point tunnels, so DS-Lite needs to define a new tunnel type 💅.

however, the NATV2-MIB and IP Tunnel MIB together aren't enough to support DS-Lite 😭. This document describes the DS-Lite MIB's specific features, as below ✨.

in the DS-Lite scenario, the Address Family Transition Router (AFTR) is not only the tunnel-end concentrator but also an IPv4-to-IPv4 NAT 🌈. So, as defined in [RFC6333], when IPv4 packets come back from the Internet to the AFTR, it knows how to rebuild the IPv6 encapsulation by doing a reverse lookup in the extended IPv4 NAT binding table (Section 6.6 of [RFC6333]) 🔁. The NAT binding table in the AFTR is extended to include the IPv6 address of the tunnel initiator 🫧. However, the NAT binding information in the NATV2-MIB, natv2PortMapTable, is indexed by the NAT instance, protocol, and external realm and address 🧩. Because the tunnelIfTable defined in the TUNNEL-MIB [RFC4087] is indexed by ifIndex, the DS-Lite MIB needs to define tunnel objects that extend the NAT binding entry by interface 🔑. So a combined MIB is necessary 💖.

an implementation of the IP Tunnel MIB is required for DS-Lite 🎀. Since the tunnel isn't point-to-point in DS-Lite, it needs to define a new tunnel type for DS-Lite 🦋. The tunnelIfEncapsMethod in the tunnelIfEntry should be set to dsLite(17), and a corresponding entry in the DS-Lite module will exist for every tunnelIfEntry with this tunnelIfEncapsMethod 🧚. The tunnelIfRemoteInetAddress must be set to "::" 🫶.

6. Structure of the MIB Module 🧩

the DS-Lite MIB gives you a way to monitor and manage the devices (AFTRs) in a DS-Lite scenario through SNMP 📡.

the DS-Lite MIB is configurable on a per-interface basis 🔌. It depends on several parts of the IF-MIB [RFC2863], IP Tunnel MIB [RFC4087], and NATV2-MIB [RFC7659] 🌸.

6.1. The Object Group 💅

this group defines the objects that the DS-Lite MIB needs ✨.

6.1.1. The dsliteTunnel Subtree 🚇

the dsliteTunnel subtree describes managed objects for managing tunnels in the DS-Lite scenario 🫧. Because tunnelInetConfigLocalAddress and tunnelInetConfigRemoteAddress, defined in the IP Tunnel MIB, are not readable, a few new objects are defined in the DS-Lite MIB 🙈.

6.1.2. The dsliteNAT Subtree 🌈

the dsliteNAT subtree describes managed objects for configuring and monitoring an AFTR that can do NAT 🔁. Because the NATV2-MIB supports NAT management in DS-Lite, the DS-Lite MIB can reuse it 🫶. The dsliteNAT subtree also maps between the tunnel entry (dsliteTunnelEntry) and the NAT entry (dsliteNATBindEntry) by adding the IPv6 address of the B4 to the natv2PortMapEntry in the NATV2-MIB 🧚. The mapping, filtering, and pooling behaviours described in this subtree are all defined in [RFC4787] 💖.

6.1.3. The dsliteInfo Subtree 📊

the dsliteInfo subtree gives you statistical info for DS-Lite 🍓.

6.2. The Notification Group 🔔

this group defines some notification objects for a DS-Lite scenario 💜.

6.3. The Conformance Group 🎀

the dsliteConformance subtree gives you conformance info for the MIB objects 🦋.

7. MIB Modules Required for IMPORTS 🧲

this MIB module IMPORTs objects from [RFC2578], [RFC2580], [RFC2863], [RFC3411], [RFC4001], and [RFC7659] ✨.

Okay bestie, this is the good stuff. We're deep in the actual MIB module now, so the code below is copied exactly as it is in the spec, and I'm just adding my commentary around it. 🎀

      dsliteMIB MODULE-IDENTITY
      LAST-UPDATED "201605110000Z"          -- May 11, 2016
      ORGANIZATION "IETF Softwire Working Group"
      CONTACT-INFO
         "Yu Fu
          CNNIC
          No.4 South 4th Street, Zhongguancun
          Hai-Dian District, Beijing  100090
          China
          Email: fuyu@cnnic.cn

          Sheng Jiang
          Huawei Technologies Co., Ltd
          Huawei Building, 156 Beiqing Rd.
          Hai-Dian District, Beijing  100095
          China
          Email: jiangsheng@huawei.com
          Jiang Dong
          Tsinghua University
          Department of Computer Science, Tsinghua University
          Beijing  100084
          China
          Email: knight.dongjiang@gmail.com

          Yuchi Chen
          Tsinghua University
          Department of Computer Science, Tsinghua University
          Beijing  100084
          China
          Email: flashfoxmx@gmail.com "

      DESCRIPTION
         "The MIB module is defined for management of objects in the
         DS-Lite scenario.

        Copyright (c) 2016 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)."
      REVISION    "201605110000Z"
      DESCRIPTION
         "Initial version.  Published as RFC 7870."
         ::=  {  mib-2 240  }


   --Top-level components of this MIB module

      dsliteMIBObjects OBJECT IDENTIFIER
         ::=  { dsliteMIB 1 }
      dsliteTunnel   OBJECT IDENTIFIER
         ::=  { dsliteMIBObjects 1 }

      dsliteNAT   OBJECT IDENTIFIER
         ::=  { dsliteMIBObjects 2 }

      dsliteInfo   OBJECT IDENTIFIER
         ::=  { dsliteMIBObjects 3 }

   --Notifications section

      dsliteNotifications  OBJECT IDENTIFIER
         ::=  { dsliteMIB 0 }


   --dsliteTunnel

   --dsliteTunnelTable

      dsliteTunnelTable OBJECT-TYPE
         SYNTAX     SEQUENCE OF DsliteTunnelEntry
         MAX-ACCESS  not-accessible
         STATUS     current
         DESCRIPTION
            "The (conceptual) table containing information on
             configured tunnels.  This table can be used to map
             a B4 address to the associated AFTR address.  It can
             also be used for row creation."
         REFERENCE
            "B4, AFTR: RFC 6333."
         ::=  { dsliteTunnel 1 }

      dsliteTunnelEntry OBJECT-TYPE
         SYNTAX     DsliteTunnelEntry
         MAX-ACCESS  not-accessible
         STATUS     current
         DESCRIPTION
            "Each entry in this table contains the information on a
             particular configured tunnel."
             INDEX   { dsliteTunnelAddressType,
                       dsliteTunnelStartAddress,
                       dsliteTunnelEndAddress,
                       ifIndex }
         ::=  { dsliteTunnelTable 1 }

      DsliteTunnelEntry  ::=
         SEQUENCE {
          dsliteTunnelAddressType         InetAddressType,
          dsliteTunnelStartAddress        InetAddress,
          dsliteTunnelEndAddress          InetAddress,
          dsliteTunnelStartAddPreLen      InetAddressPrefixLength
      }

       dsliteTunnelAddressType OBJECT-TYPE
          SYNTAX     InetAddressType
          MAX-ACCESS not-accessible
          STATUS     current
          DESCRIPTION
             "This object MUST be set to the value of ipv6(2).

              It describes the address type of the IPv4-in-IPv6
              tunnel initiator and endpoint."
          REFERENCE
            "ipv6(2): RFC 4001."
          ::= { dsliteTunnelEntry 1 }

      dsliteTunnelStartAddress OBJECT-TYPE
          SYNTAX     InetAddress (SIZE (0..16))
          MAX-ACCESS not-accessible
          STATUS     current
          DESCRIPTION
             "The IPv6 address of the initiator of the tunnel.
              The address type is given by dsliteTunnelAddressType."
          ::= { dsliteTunnelEntry 2 }

      dsliteTunnelEndAddress OBJECT-TYPE
          SYNTAX     InetAddress (SIZE (0..16))
          MAX-ACCESS not-accessible
          STATUS     current
          DESCRIPTION
             "The IPv6 address of the endpoint of the tunnel.
              The address type is given by dsliteTunnelAddressType."
          ::= { dsliteTunnelEntry 3 }

      dsliteTunnelStartAddPreLen OBJECT-TYPE
          SYNTAX InetAddressPrefixLength
          MAX-ACCESS read-only
          STATUS current
          DESCRIPTION
             "The IPv6 prefix length of the IP address for the
              initiator of the tunnel(dsliteTunnelStartAddress)."
          ::= { dsliteTunnelEntry 4 }


    --dsliteNATBindTable(according to the NAPT scheme)

       dsliteNATBindTable OBJECT-TYPE
         SYNTAX     SEQUENCE OF DsliteNATBindEntry
         MAX-ACCESS not-accessible
         STATUS     current
         DESCRIPTION
            "This table contains information about currently
             active NAT binds in the NAT of the AFTR.  This table
             adds the IPv6 address of a B4 to the natv2PortMapTable
             defined in NATV2-MIB (RFC 7659)."
         REFERENCE
              "NATV2-MIB: Section 4 of RFC 7659."
         ::=  { dsliteNAT 1 }

      dsliteNATBindEntry OBJECT-TYPE
         SYNTAX     DsliteNATBindEntry
         MAX-ACCESS not-accessible
         STATUS     current
         DESCRIPTION
            "The entry in this table holds the mapping relationship
             between tunnel information and NAT bind information.
             Each entry in this table not only needs to match a
             corresponding entry in the natv2PortMapTable, but
             also a corresponding entry in the dsliteTunnelTable.
             So, the INDEX of the entry needs to match a corresponding
             value in the natv2PortMapTable INDEX and a corresponding
             value in the dsliteTunnelTable INDEX.  These entries are
             lost upon agent restart."
         REFERENCE
              "natv2PortMapTable: Section 4 of RFC 7659."
         INDEX   { dsliteNATBindMappingInstanceIndex,
                   dsliteNATBindMappingProto,
                   dsliteNATBindMappingExtRealm,
                   dsliteNATBindMappingExtAddressType,
                   dsliteNATBindMappingExtAddress,
                   dsliteNATBindMappingExtPort,
                   ifIndex,
                   dsliteTunnelStartAddress }
         ::=  {  dsliteNATBindTable 1   }

     DsliteNATBindEntry  ::=
         SEQUENCE {
         dsliteNATBindMappingInstanceIndex  Natv2InstanceIndex,
         dsliteNATBindMappingProto          ProtocolNumber,
         dsliteNATBindMappingExtRealm       SnmpAdminString,
         dsliteNATBindMappingExtAddressType InetAddressType,
         dsliteNATBindMappingExtAddress     InetAddress,
         dsliteNATBindMappingExtPort        InetPortNumber,
         dsliteNATBindMappingIntRealm       SnmpAdminString,
         dsliteNATBindMappingIntAddressType InetAddressType,
         dsliteNATBindMappingIntAddress     InetAddress,
         dsliteNATBindMappingIntPort        InetPortNumber,
         dsliteNATBindMappingPool           Unsigned32,
         dsliteNATBindMappingMapBehavior    INTEGER,
         dsliteNATBindMappingFilterBehavior INTEGER,
         dsliteNATBindMappingAddressPooling INTEGER
         }

      dsliteNATBindMappingInstanceIndex OBJECT-TYPE
          SYNTAX Natv2InstanceIndex
          MAX-ACCESS not-accessible
          STATUS current
          DESCRIPTION
             "Index of the NAT instance that created this port
              map entry."
       ::= { dsliteNATBindEntry 1 }

      dsliteNATBindMappingProto OBJECT-TYPE
          SYNTAX      ProtocolNumber
          MAX-ACCESS  not-accessible
          STATUS      current
          DESCRIPTION
             "This object specifies the mapping's transport protocol
              number."
          ::= { dsliteNATBindEntry 2 }

     dsliteNATBindMappingExtRealm OBJECT-TYPE
          SYNTAX     SnmpAdminString (SIZE(0..32))
          MAX-ACCESS not-accessible
          STATUS     current
          DESCRIPTION
             "The realm to which dsliteNATBindMappingExtAddress
             belongs."
          ::= { dsliteNATBindEntry 3 }

      dsliteNATBindMappingExtAddressType OBJECT-TYPE
          SYNTAX InetAddressType
          MAX-ACCESS not-accessible
          STATUS current
          DESCRIPTION
            "Address type for the mapping's external address.
             This object MUST be set to the value of iPv4(1).
             The values of ipv6(2), ipv4z(3), and ipv6z(4) are
             not allowed."
          REFERENCE
            "ipv4(1), ipv6(2), iPv4z(3), and ipv6z(4): RFC 4001."
          ::= { dsliteNATBindEntry 4 }

     dsliteNATBindMappingExtAddress OBJECT-TYPE
          SYNTAX InetAddress (SIZE (0..4))
          MAX-ACCESS not-accessible
          STATUS current
          DESCRIPTION
            "The mapping's external address.  This is the source
             address for translated outgoing packets.  The address
             type is given by dsliteNATBindMappingExtAddressType."
          ::= { dsliteNATBindEntry 5 }

      dsliteNATBindMappingExtPort OBJECT-TYPE
          SYNTAX InetPortNumber
          MAX-ACCESS not-accessible
          STATUS current
          DESCRIPTION
            "The mapping's assigned external port number.
             This is the source port for translated outgoing
             packets.  This MUST be a non-zero value."
          ::= { dsliteNATBindEntry 6 }

       dsliteNATBindMappingIntRealm OBJECT-TYPE
          SYNTAX SnmpAdminString (SIZE(0..32))
          MAX-ACCESS read-only
          STATUS current
          DESCRIPTION
            "The realm to which natMappingIntAddress belongs.  This
             realm defines the IPv6 address space from which the
             tunnel source address is taken.  The realm of the
             encapsulated IPv4 address is restricted in scope to
             the tunnel, so there is no point in identifying it
             separately."
          ::= { dsliteNATBindEntry 7 }

    dsliteNATBindMappingIntAddressType OBJECT-TYPE
          SYNTAX InetAddressType
          MAX-ACCESS read-only
          STATUS current
          DESCRIPTION
             "Address type of the mapping's internal address.
             This object MUST be set to the value of iPv4z(3).
             The values of ipv4(1), ipv6(2), and ipv6z(4) are
             not allowed."
          REFERENCE
            "ipv4(1), ipv6(2), iPv4z(3), and ipv6z(4): RFC 4001."
          ::= { dsliteNATBindEntry 8 }

      dsliteNATBindMappingIntAddress OBJECT-TYPE
          SYNTAX InetAddress
          MAX-ACCESS read-only
          STATUS current
          DESCRIPTION
            "The mapping's internal address.  It is the IPv6 tunnel
             source address.  The address type is given by
             dsliteNATBindMappingIntAddressType."
          ::= { dsliteNATBindEntry 9 }

      dsliteNATBindMappingIntPort OBJECT-TYPE
          SYNTAX InetPortNumber
          MAX-ACCESS read-only
          STATUS current
          DESCRIPTION
           "The mapping's internal port number.  This MUST be a
            non-zero value."
           ::= { dsliteNATBindEntry 10 }

      dsliteNATBindMappingPool OBJECT-TYPE
          SYNTAX Unsigned32 (0|1..4294967295)
          MAX-ACCESS read-only
          STATUS current
          DESCRIPTION
            "Index of the pool that contains this mapping's external
             address and port.  If zero, no pool is associated with
             this mapping."
          ::= { dsliteNATBindEntry 11 }

Heads up, this chunk is where the MUSTs live! 💅 Five of them show up in here: the tunnel address type has to be ipv6(2), the NAT external address type has to be iPv4(1), the external port can't be zero, the internal address type has to be iPv4z(3), and the internal port can't be zero either. 🫶 Since the spec is the source of truth, I kept every one exactly as written, and they're still in capitals inside the code so nobody can accidentally soften them. 🔥

okay bestie, the MIB objects are back and they're doing a lot 💅✨

      dsliteNATBindMappingMapBehavior OBJECT-TYPE
          SYNTAX INTEGER{
          endpointIndependent (0),
          addressDependent(1),
          addressAndPortDependent (2)
          }
          MAX-ACCESS read-only
          STATUS current
          DESCRIPTION
            "Mapping behavior as described in Section 4.1 of RFC 4787.

             endpointIndependent(0), the behavior REQUIRED by
             RFC 4787, REQ-1 maps the source address and port to
             the same external address and port for all destination
             address and port combinations reached through the same
             external realm and using the given protocol.

             addressDependent(1) maps to the same external address
             and port for all destination ports at the same
             destination address reached through the same external
             realm and using the given protocol.

             addressAndPortDependent(2) maps to a separate external
             address and port combination for each different
             destination address and port combination reached
             through the same external realm.

             For the DS-Lite scenario, it must be
             addressAndPortDependent(2)."
          REFERENCE
            "Mapping behavior: Section 4.1 of RFC 4787.
             DS-Lite: RFC 6333."
          ::= { dsliteNATBindEntry 12 }

      dsliteNATBindMappingFilterBehavior OBJECT-TYPE
          SYNTAX INTEGER{
          endpointIndependent (0),
          addressDependent(1),
          addressAndPortDependent (2)
          }
          MAX-ACCESS read-only
          STATUS current
          DESCRIPTION
            "Filtering behavior as described in Section 5 of RFC 4787.

             endpointIndependent(0) accepts for translation packets
             from all combinations of remote address and port
             destined to the mapped external address and port via
             the given external realm and using the given protocol.

             addressDependent(1) accepts for translation packets from
             all remote ports from the same remote source address
             destined to the mapped external address and port via the
             given external realm and using the given protocol.

             addressAndPortDependent(2) accepts for translation only
             those packets with the same remote source address, port,
             and protocol incoming from the same external realm as
             identified when the applicable port map entry was
             created.

             RFC 4787, REQ-8 recommends either endpointIndependent(0)
             or addressDependent(1) filtering behavior, depending on
             whether application friendliness or security takes
             priority.

             For the DS-Lite scenario, it must be
             addressAndPortDependent(2)."
          REFERENCE
            "Filtering behavior: Section 5 of RFC 4787.
             DS-Lite: RFC 6333."
          ::= { dsliteNATBindEntry 13 }

      dsliteNATBindMappingAddressPooling OBJECT-TYPE
          SYNTAX INTEGER{
          arbitrary (0),
          paired (1)
          }
          MAX-ACCESS read-only
          STATUS current
          DESCRIPTION
            "Type of address pooling behavior that was used to create
             this mapping.

             arbitrary(0) pooling behavior means that the NAT instance
             may create the new port mapping using any address in the
             pool that has a free port for the protocol concerned.

             paired(1) pooling behavior, the behavior RECOMMENDED by RFC
             4787, REQ-2 means that once a given internal address has
             been mapped to a particular address in a particular pool,
             further mappings of the same internal address to that pool
             will reuse the previously assigned pool member address."
          REFERENCE
            "Pooling behavior: Section 4.1 of RFC 4787."
          ::= { dsliteNATBindEntry 14 }


      --dsliteInfo

      dsliteAFTRAlarmScalar OBJECT IDENTIFIER ::= { dsliteInfo 1 }

      dsliteAFTRAlarmB4AddrType OBJECT-TYPE
         SYNTAX  InetAddressType
         MAX-ACCESS accessible-for-notify
         STATUS current
         DESCRIPTION
            "This object indicates the address type of
             the B4, which will send an alarm."
         ::= { dsliteAFTRAlarmScalar 1 }

      dsliteAFTRAlarmB4Addr OBJECT-TYPE
         SYNTAX  InetAddress
         MAX-ACCESS accessible-for-notify
         STATUS current
         DESCRIPTION
            "This object indicates the IP address of
             B4, which will send an alarm.  The address type is
             given by dsliteAFTRAlarmB4AddrType."
         ::= { dsliteAFTRAlarmScalar 2 }

      dsliteAFTRAlarmProtocolType OBJECT-TYPE
         SYNTAX INTEGER{
         tcp (0),
         udp (1),
         icmp (2),
         total (3)
         }
         MAX-ACCESS accessible-for-notify
         STATUS current
         DESCRIPTION
            "This object indicates the transport protocol type
             of alarm.

             tcp (0) means that the transport protocol type of
             alarm is tcp.

             udp (1) means that the transport protocol type of
             alarm is udp.

             icmp (2) means that the transport protocol type of
             alarm is icmp.

             total (3) means that the transport protocol type of
             alarm is total."
         ::= { dsliteAFTRAlarmScalar 3 }

    dsliteAFTRAlarmSpecificIPAddrType OBJECT-TYPE
         SYNTAX InetAddressType
         MAX-ACCESS accessible-for-notify
         STATUS current
         DESCRIPTION
            "This object indicates the address type of the IP address
             whose port usage has reached the threshold."
         ::= { dsliteAFTRAlarmScalar 4 }

     dsliteAFTRAlarmSpecificIP OBJECT-TYPE
         SYNTAX InetAddress
         MAX-ACCESS accessible-for-notify
         STATUS current
         DESCRIPTION
            "This object indicates the IP address whose port usage
             has reached the threshold.  The address type is given by
             dsliteAFTRAlarmSpecificIPAddrType."
         ::= { dsliteAFTRAlarmScalar 5 }

      dsliteAFTRAlarmConnectNumber OBJECT-TYPE
         SYNTAX Integer32 (60..90)
         MAX-ACCESS read-write
         STATUS current
         DESCRIPTION
            "This object indicates the notification threshold
             of the DS-Lite tunnels that is active in
             the AFTR device."
          REFERENCE
            "AFTR: Section 6 of RFC 6333."

         DEFVAL
             { 60 }
         ::= { dsliteAFTRAlarmScalar 6 }

      dsliteAFTRAlarmSessionNumber OBJECT-TYPE
         SYNTAX Integer32
         MAX-ACCESS read-write
         STATUS current
         DESCRIPTION
            "This object indicates the notification threshold of
             the IPv4 session for the user."
          REFERENCE
            "AFTR: Section 6 of RFC 6333
             B4: Section 5 of RFC 6333."
         DEFVAL
             { -1 }
         ::= { dsliteAFTRAlarmScalar 7 }

     dsliteAFTRAlarmPortNumber OBJECT-TYPE
         SYNTAX Integer32
         MAX-ACCESS read-write
         STATUS current
         DESCRIPTION
            "This object indicates the notification threshold of the NAT
             ports that have been used by the user."
         DEFVAL
             { -1 }
         ::= { dsliteAFTRAlarmScalar 8 }

      dsliteStatisticsTable OBJECT-TYPE
         SYNTAX SEQUENCE OF DsliteStatisticsEntry
         MAX-ACCESS not-accessible
         STATUS current
         DESCRIPTION
            "This table provides statistical information
             about DS-Lite."
         ::= { dsliteInfo 2 }

      dsliteStatisticsEntry OBJECT-TYPE
         SYNTAX DsliteStatisticsEntry
         MAX-ACCESS not-accessible
         STATUS current
         DESCRIPTION
            "Each entry in this table provides statistical information
             about DS-Lite."
         INDEX { dsliteStatisticsSubscriberIndex }
         ::= { dsliteStatisticsTable 1 }

      DsliteStatisticsEntry ::=
         SEQUENCE {
       dsliteStatisticsSubscriberIndex        Natv2SubscriberIndex,
       dsliteStatisticsDiscards               Counter64,
       dsliteStatisticsSends                  Counter64,
       dsliteStatisticsReceives               Counter64,
       dsliteStatisticsIpv4Session            Counter64,
       dsliteStatisticsIpv6Session            Counter64
      }

     dsliteStatisticsSubscriberIndex OBJECT-TYPE
        SYNTAX Natv2SubscriberIndex
        MAX-ACCESS not-accessible
        STATUS current
        DESCRIPTION
           "Index of the subscriber or host.  A unique value,
            greater than zero, for each subscriber in the
            managed system."
         ::= { dsliteStatisticsEntry 1 }

      dsliteStatisticsDiscards OBJECT-TYPE
         SYNTAX Counter64
         MAX-ACCESS read-only
         STATUS current
         DESCRIPTION
            "This object indicates the number of packets
             discarded from this subscriber."
        ::= { dsliteStatisticsEntry 2 }

       dsliteStatisticsSends  OBJECT-TYPE
         SYNTAX Counter64
         MAX-ACCESS read-only
         STATUS current
         DESCRIPTION
            "This object indicates the number of packets that is
              sent to this subscriber."
         ::= { dsliteStatisticsEntry 3 }

       dsliteStatisticsReceives  OBJECT-TYPE
         SYNTAX Counter64
         MAX-ACCESS read-only
         STATUS current
         DESCRIPTION
            "This object indicates the number of packets that is
              received from this subscriber."
         ::= { dsliteStatisticsEntry 4 }

      dsliteStatisticsIpv4Session OBJECT-TYPE
         SYNTAX Counter64
         MAX-ACCESS read-only
         STATUS current
         DESCRIPTION
            "This object indicates the number of the
             current IPv4 Sessions."
         REFERENCE
             "Session: Paragraph 2 in Section 11 of RFC 6333.
             (The AFTR should have the capability to log the
              tunnel-id, protocol, ports/IP addresses, and
              the creation time of the NAT binding to uniquely
              identify the user sessions)."
         ::= { dsliteStatisticsEntry 5 }

      dsliteStatisticsIpv6Session OBJECT-TYPE
         SYNTAX Counter64
         MAX-ACCESS read-only
         STATUS current
         DESCRIPTION
            "This object indicates the number of the
             current IPv6 session.  Because the AFTR is
             also a dual-stack device, it will also
             forward normal IPv6 packets for the
             inbound and outbound direction."
         REFERENCE
             "Session: Paragraph 2 in Section 11 of RFC 6333.
             (The AFTR should have the capability to log the
              tunnel-id, protocol, ports/IP addresses, and
              the creation time of the NAT binding to uniquely
              identify the user sessions)."
        ::= { dsliteStatisticsEntry 6 }

   ---dslite Notifications

      dsliteTunnelNumAlarm NOTIFICATION-TYPE
         OBJECTS { dsliteAFTRAlarmProtocolType,
                   dsliteAFTRAlarmB4AddrType,
                   dsliteAFTRAlarmB4Addr }
         STATUS current
         DESCRIPTION
            "This trap is triggered when the number of
             current DS-Lite tunnels exceeds the value of
             the dsliteAFTRAlarmConnectNumber."
         ::= { dsliteNotifications 1 }

that's the end of this batch, so much MIB goodness 🦋💜 more parts are coming, so stay tuned 🧚

      dsliteAFTRUserSessionNumAlarm NOTIFICATION-TYPE
         OBJECTS { dsliteAFTRAlarmProtocolType,
                dsliteAFTRAlarmB4AddrType,
                dsliteAFTRAlarmB4Addr }
         STATUS current
         DESCRIPTION
            "This trap is triggered when user sessions
             reach the threshold.  The threshold
             is specified by the dsliteAFTRAlarmSessionNumber."
         REFERENCE
             "Session: Paragraph 2 in Section 11 of RFC 6333.
             (The AFTR should have the capability to log the
              tunnel-id, protocol, ports/IP addresses, and
              the creation time of the NAT binding to uniquely
              identify the user sessions)."
         ::= { dsliteNotifications 2 }

        dsliteAFTRPortUsageOfSpecificIpAlarm NOTIFICATION-TYPE
         OBJECTS { dsliteAFTRAlarmSpecificIPAddrType,
                    dsliteAFTRAlarmSpecificIP }
         STATUS current
         DESCRIPTION
            "This trap is triggered when the used NAT
             ports of map address reach the threshold.
             The threshold is specified by the
             dsliteAFTRAlarmPortNumber."
         ::= { dsliteNotifications 3 }

   --Module Conformance statement

      dsliteConformance   OBJECT IDENTIFIER
         ::=  { dsliteMIB 2 }

      dsliteCompliances OBJECT IDENTIFIER ::= { dsliteConformance 1 }

      dsliteGroups OBJECT IDENTIFIER ::= { dsliteConformance 2 }

   -- compliance statements

      dsliteCompliance MODULE-COMPLIANCE
          STATUS current
          DESCRIPTION
              "Describes the minimal requirements for conformance
               to the DS-Lite MIB."
          MODULE -- this module
              MANDATORY-GROUPS { dsliteNATBindGroup,
                  dsliteTunnelGroup,
                  dsliteStatisticsGroup,
                  dsliteNotificationsGroup,
                  dsliteAFTRAlarmScalarGroup }
          ::= { dsliteCompliances 1 }

      dsliteNATBindGroup OBJECT-GROUP
         OBJECTS {
                  dsliteNATBindMappingIntRealm,
                  dsliteNATBindMappingIntAddressType,
                  dsliteNATBindMappingIntAddress,
                  dsliteNATBindMappingIntPort,
                  dsliteNATBindMappingPool,
                  dsliteNATBindMappingMapBehavior,
                  dsliteNATBindMappingFilterBehavior,
                  dsliteNATBindMappingAddressPooling }
         STATUS current
         DESCRIPTION
             "A collection of objects to support basic
              management of NAT binds in the NAT of the AFTR."
          ::= { dsliteGroups 1 }

      dsliteTunnelGroup OBJECT-GROUP
         OBJECTS { dsliteTunnelStartAddPreLen }
         STATUS current
         DESCRIPTION
             "A collection of objects to support management
              of DS-Lite tunnels."
         ::= { dsliteGroups 2 }

      dsliteStatisticsGroup OBJECT-GROUP
         OBJECTS { dsliteStatisticsDiscards,
                   dsliteStatisticsSends,
                   dsliteStatisticsReceives,
                   dsliteStatisticsIpv4Session,
                   dsliteStatisticsIpv6Session }
        STATUS current
        DESCRIPTION
           " A collection of objects to support management
             of statistical information for AFTR devices."
          ::= { dsliteGroups 3 }

      dsliteNotificationsGroup NOTIFICATION-GROUP
         NOTIFICATIONS { dsliteTunnelNumAlarm,
                         dsliteAFTRUserSessionNumAlarm,
                         dsliteAFTRPortUsageOfSpecificIpAlarm }
         STATUS current
         DESCRIPTION
            "A collection of objects to support management
             of trap information for AFTR devices."

         ::= { dsliteGroups 4 }

       dsliteAFTRAlarmScalarGroup OBJECT-GROUP
         OBJECTS { dsliteAFTRAlarmB4AddrType,
              dsliteAFTRAlarmB4Addr,
              dsliteAFTRAlarmProtocolType,
              dsliteAFTRAlarmSpecificIPAddrType,
              dsliteAFTRAlarmSpecificIP,
              dsliteAFTRAlarmConnectNumber,
              dsliteAFTRAlarmSessionNumber,
              dsliteAFTRAlarmPortNumber}
         STATUS current
         DESCRIPTION
             "A collection of objects to support management of
             the information about the AFTR alarming scalar."
         ::= { dsliteGroups 5 }

             END

9. Security Considerations 🔒💖

Okay bestie, this part is SERIOUS, so read it carefully 🥺. There are a bunch of management objects in this MIB module with a MAX-ACCESS of read-write and/or read-create. Those objects can be sensitive or vulnerable depending on where the network lives. Supporting SET operations in a non-secure environment without proper protection opens devices up to attack 💀. These are the tables and objects, plus their sensitivity/vulnerability:

  • dsliteAFTRAlarmConnectNumber
  • dsliteAFTRAlarmSessionNumber
  • dsliteAFTRAlarmPortNumber

Notification thresholds: an attacker who sets an arbitrarily low threshold can cause loads of useless notifications to be generated 📢. Setting an arbitrarily high threshold can effectively turn notifications off, and that could be used to hide another attack 🙈. Not it!

Some of the readable objects in this MIB module (so, objects with a MAX-ACCESS other than not-accessible) can also be sensitive or vulnerable in some network environments. It's super important to control even GET and/or NOTIFY access to these objects, and it may even be worth encrypting their values when they're sent over the network via SNMP 🔐. These are the tables and objects, plus their sensitivity/vulnerability:

  • entries in dsliteTunnelTable
  • entries in dsliteNATBindTable

Objects that reveal host identities: various objects can reveal the identity of private hosts that are in a session with external end nodes 👀. A curious outsider could watch these to figure out how many private hosts the AFTR device is supporting. Even worse, a disgruntled former employee of an enterprise could use that info to break into specific private hosts, either by intercepting existing sessions or by starting new sessions into the host 😱. At the very least, unauthorized monitoring of these objects violates individual subscribers' privacy 🫶.

Unauthorized read access to the dsliteTunnelTable would reveal information about the tunnel topology 🗺️.

SNMP versions before SNMPv3 did not include adequate security 💀. Even if the network itself is secure (for example, by using IPsec), there's no control over who on that secure network gets to access and GET/SET (read/change/create/delete) the objects in this MIB module. Main character villain behavior 🥀.

Implementations SHOULD provide the security features described by the SNMPv3 framework (see [RFC3410]), and implementations claiming compliance to the SNMPv3 standard MUST include full support for authentication and privacy via the User-based Security Model (USM) [RFC3414] with the AES cipher algorithm [RFC3826]. Implementations MAY also provide support for the Transport Security Model (TSM) [RFC5591] in combination with a secure transport such as SSH [RFC5592] or TLS/DTLS [RFC6353] ✨.

Further, deployment of SNMP versions prior to SNMPv3 is NOT RECOMMENDED. Instead, it is RECOMMENDED to deploy SNMPv3 and to enable cryptographic security 💅. It is then a customer/operator responsibility to make sure the SNMP entity giving access to an instance of this MIB module is configured so that access to the objects is only given to those principals (users) who have legitimate rights to actually GET or SET (change/create/delete) them 🧚.

10. IANA Considerations 🗂️

IANA has allocated the following OBJECT IDENTIFIER value and recorded it in the SMI Numbers registry, in the subregistry called "SMI Network Management MGMT Codes Internet-standard MIB" under the mib-2 branch (1.3.6.1.2.1) 🌸:

      Descriptor        OBJECT IDENTIFIER value
      ----------        -----------------------
      DSLite-MIB         { mib-2 240 }

IANA has also recorded the following IANAtunnelType Textual Convention within the IANAifType-MIB 🦋:

      IANAtunnelType ::= TEXTUAL-CONVENTION
                 SYNTAX     INTEGER {
                            dsLite(17)        -- DS-Lite tunnel
                            }

11. References 📚

The reference list keeps going in the next part, bestie 🫶.

11.1. Normative References 📚✨

Okay bestie, these are the docs you need in your back pocket to read this one properly 🫶

11.2. Informative References 💡

Just a little extra reading for the curious 🧚

Acknowledgements 🫶💖

The authors are so grateful to these people for their super valuable comments: Suresh Krishnan, Ian Farrer, Yiu Lee, Qi Sun, Yong Cui, David Harrington, Dave Thaler, Tassos Chatzithomaoglou, Tom Taylor, Hui Deng, Carlos Pignataro, Matt Miller, Terry Manderson, and the rest of the Softwire working group 🌸 literally a whole squad 👑

Authors' Addresses 💌

Yu Fu CNNIC No.4 South 4th Street, Zhongguancun Hai-Dian District, Beijing 100190 China

Email: fuyu@cnnic.cn

Sheng Jiang Huawei Technologies Co., Ltd Q14, Huawei Campus, No.156 Beiqing Road Hai-Dian District, Beijing 100095 China

Email: jiangsheng@huawei.com

Jiang Dong Tsinghua University Department of Computer Science, Tsinghua University Beijing 100084 China

Email: knight.dongjiang@gmail.com

Yuchi Chen Tsinghua University Department of Computer Science, Tsinghua University Beijing 100084 China

Email: flashfoxmx@gmail.com

That's the whole RFC, bestie 🌈✨ we did it 😭🎀

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