RFC 6165
Extensions to IS-IS for Layer-2 Systems
RFC 6165: Extensions to IS-IS for Layer-2 Systems 🦋✨
okay bestie, let's get into this one 💅 it's RFC 6165, published April 2011 as a Standards Track doc (so it's the real deal, not just vibes 🔥). The authors are Ayan Banerjee from Cisco Systems and David Ward from Juniper Networks 🫶. It doesn't obsolete or update anything, and it's giving ISSN 2070-1721 energy 🌈.
Abstract 🎀
okay so this doc is all about IS-IS extensions that let link state routing work for any protocol running directly over Layer-2 💖. there are a few pieces to making that happen, but this RFC only covers the IS-IS part 💅. the TLVs it describes are generic Layer-2 additions, and anything more specific gets defined in the IS-IS technology-specific extensions 🧚. it's up to the systems using these extensions to explain how the info gets used ✨.
Status of This Memo 🌸
this is an Internet Standards Track document 💜. it's a product of the IETF and reflects the consensus of the IETF community, it got public review, and the IESG approved it for publication 🔥. more info on Internet Standards is in Section 2 of RFC 5741 🍓. the current status, errata, and feedback info live at http://www.rfc-editor.org/info/rfc6165 🦋.
Copyright Notice 🌈
Copyright (c) 2011 IETF Trust and the persons identified as the document authors 💅. all rights reserved, bestie 🫶. this doc is subject to BCP 78 and the IETF Trust's Legal Provisions Relating to IETF Documents (http://trustee.ietf.org/license-info) as they were on the publication date, so read those carefully because they spell out your rights 🙈. any Code Components pulled out of this doc have to include the Simplified BSD License text from Section 4.e of the Trust Legal Provisions, and they come with no warranty as described in that license ⭐.
Table of Contents 🧚
1. Overview ........................................................2
1.1. Terminology ................................................3
2. TLV Enhancements to IS-IS .......................................3
2.1. Multi-Topology-Aware Port Capability TLV ...................3
2.2. The MAC-Reachability TLV ...................................4
3. Acknowledgements ................................................5
4. Security Considerations .........................................5
5. IANA Considerations .............................................5
6. References ......................................................6
6.1. Normative References .......................................6
6.2. Informative References .....................................61. Overview 🌸
okay so a bunch of systems (like [RBRIDGES], [802.1aq], and [OTV]) carry Layer-2 addresses inside a link state routing protocol, specifically Intermediate System to Intermediate System [IS-IS] [RFC1195], so they can do true Layer-2 routing 💖. almost all of these technologies wrap the classic Layer-2 packets in an outer header, and that outer header format is different across all of them 🎀. that outer header is what gets the encapsulated packets to where they're going ✨.
each Intermediate System (IS) advertises one or more IS-IS Link State Protocol Data Units (PDUs) with routing info 🧚. each Link State PDU (LSP) has a fixed header plus a bunch of tuples, and each tuple is a Type, a Length, and a Value 🦋. those tuples are called TLVs 💅. this doc sets out a group of TLVs to add to [IS-IS] PDUs so these systems can work 🔥. the TLVs are generic Layer-2 additions, and specific ones get defined in the IS-IS technology-specific extensions as needed 🌈. this doc does NOT propose any new forwarding mechanisms that use this extra info carried in IS-IS 🙈.
1.1. Terminology 💜
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this document are to be interpreted as described in RFC 2119 [RFC2119] 💖.
2. TLV Enhancements to IS-IS 🎀
this section lays out the enhancements to the TLVs that Layer-2 technologies need in common 💅.
2.1. Multi-Topology-Aware Port Capability TLV 🧚
The Multi-Topology-aware Port Capability (MT-PORT-CAP) is IS-IS TLV type 143 and it looks like this 🦋:
+-+-+-+-+-+-+-+-+
| Type=MTPORTCAP| (1 byte)
+-+-+-+-+-+-+-+-+
| Length | (1 byte)
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|R|R|R|R| Topology Identifier | (2 bytes)
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| sub-TLVs (variable bytes) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+the fields, bestie 💅:
Type: the TLV Type, set to MT-PORT-CAP TLV 143 🎀.Length: the total number of bytes in the value field, including the length of the sub-TLVs carried in this TLV ✨.R: 4 reserved bits. they MUST be sent as zero and ignored on receipt 🙈.Topology Identifier: an MT ID is a 12-bit field holding the MT ID of the topology being announced 🌸. when this field is zero, it means it's carrying base topology info 🧚.Sub-TLVs: the MT-PORT-CAP TLV value has sub-TLVs formatted as described in [RFC5305] 🦋. they're defined in the technology-specific docs 💖.
the MT-PORT-CAP TLV can show up multiple times and gets carried inside an IS-IS Hello (IIH) PDU 🔥.
2.2. The MAC-Reachability TLV 🌈
The MAC-Reachability (MAC-RI) TLV is IS-IS TLV type 147 and it looks like this 💅:
+-+-+-+-+-+-+-+-+
| Type= MAC-RI | (1 byte)
+-+-+-+-+-+-+-+-+
| Length | (1 byte)
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Topology-id/Nickname | (2 bytes)
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Confidence | (1 byte)
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| RESV | VLAN-ID | (2 bytes)
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-...+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| MAC (1) (6 bytes) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-...+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| ................. |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-...+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| MAC (N) (6 bytes) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-...+-+-+-+-+-+-+-+-+-+-+-+-+-+-+the fields, bestie 💖:
Type: the TLV Type, set to 147 (MAC-RI) 🎀.Length: the total bytes in the value field, given by 5 + 6*n bytes ✨.Topology-id/Nickname: depending on the technology it's used in, this carries the topology-id or nickname 🧚. when it's set to zero, it means the MAC addresses are reachable across all topologies, or across all nicknames of the originating IS 🦋.Confidence: an 8-bit quantity showing how confident the IS is in the MAC addresses being transported 💅. whether this gets used, and what it means if it does, is defined by the specific protocol using Layer-2 IS-IS 🔥. if it's not used, it MUST be set to zero on transmission and ignored on receipt 🙈.RESV: 4 bits. they MUST be sent as zero and ignored on receipt 🌸.VLAN-ID: a 12-bit VLAN identifier that's valid for all the subsequent MAC addresses in this TLV, or zero if no VLAN is specified 🌈.MAC(i): the 48-bit MAC address reachable from the IS announcing this TLV 💜.
the MAC-RI TLV rides in a standard Link State PDU (LSP) 💅. it can show up multiple times in one LSP and across multiple LSPs ✨. it MUST contain only unicast addresses 🫶. how these TLVs get generated by the various Layer-2 routing techs, and how they get consumed, is detailed in the technology-specific docs 🧚.
in most of the technologies, these MAC-RI TLVs turn into populating the hardware with these entries, plus the right next-hop info derived from the advertising IS 🔥.
3. Acknowledgements 💖
the authors want to thank Peter Ashwood-Smith, Donald E. Eastlake 3rd, Dino Farinacci, Don Fedyk, Les Ginsberg, Radia Perlman, Mike Shand, and Russ White for their helpful comments 🫶✨.
4. Security Considerations 🙈
this doc adds no additional security risks to IS-IS, and it doesn't provide any additional security for IS-IS either 💀. read that one twice, bestie.
5. IANA Considerations 🌈
this doc specifies a set of new IS-IS TLVs: the Port-Capability TLV (type 143) and the MAC-Reachability TLV (type 147) 🦋. they're listed in the IS-IS TLV codepoint registry 💅.
IIH LSP SNP
MT-Port-Cap-TLV (143) X - -
MAC-RI TLV (147) - X -6. References 🧚
6.1. Normative References 💜
[IS-IS] ISO/IEC 10589:2002, Second Edition, "Intermediate System
to Intermediate System Intra-Domain Routing Information
Exchange Protocol for use in Conjunction with the Protocol
for Providing the Connectionless-mode Network Service
(ISO 8473)", 2002.
[RFC1195] Callon, R., "Use of OSI IS-IS for routing in TCP/IP and
dual environments", RFC 1195, December 1990.
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997.
[RFC5305] Li, T. and H. Smit, "IS-IS Extensions for Traffic
Engineering", RFC 5305, October 2008.6.2. Informative References 🌸
[802.1aq] "Standard for Local and Metropolitan Area Networks /
Virtual Bridged Local Area Networks / Amendment 8:
Shortest Path Bridging, Draft IEEE P802.1aq/D1.5", 2008.
[OTV] Grover, H., Rao, D., and D. Farinacci, "Overlay Transport
Virtualization", Work in Progress, October 2010.
[RBRIDGES]
Perlman, R., Eastlake 3rd, D., Dutt, D., Gai, S., and A.
Ghanwani, "RBridges: Base Protocol Specification", Work
in Progress, March 2010.Authors' Addresses 🎀
Ayan Banerjee
Cisco Systems
170 W. Tasman Drive
San Jose, CA 95138
USA
EMail: ayabaner@cisco.com
David Ward
Juniper Networks
1194 N. Mathilda Ave.
Sunnyvale, CA 94089-1206
USA
Phone: +1-408-745-2000
EMail: dward@juniper.net📦 where this page comes from
- ietf: rfc6165 2011-04
- 💖 girlified by claude-haiku-5-5 on : a language model's rewrite of the original, under its terms