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+Internet Engineering Task Force (IETF) A. Banerjee
+Request for Comments: 6165 Cisco Systems
+Category: Standards Track D. Ward
+ISSN: 2070-1721 Juniper Networks
+ April 2011
+
+
+ Extensions to IS-IS for Layer-2 Systems
+
+Abstract
+
+ This document specifies the Intermediate System to Intermediate
+ System (IS-IS) extensions necessary to support link state routing for
+ any protocols running directly over Layer-2. While supporting this
+ concept involves several pieces, this document only describes
+ extensions to IS-IS. Furthermore, the Type, Length, Value pairs
+ (TLVs) described in this document are generic Layer-2 additions, and
+ specific ones as needed are defined in the IS-IS technology-specific
+ extensions. We leave it to the systems using these IS-IS extensions
+ to explain how the information carried in IS-IS is used.
+
+Status of This Memo
+
+ This is an Internet Standards Track document.
+
+ This document is a product of the Internet Engineering Task Force
+ (IETF). It represents the consensus of the IETF community. It has
+ received public review and has been approved for publication by the
+ Internet Engineering Steering Group (IESG). Further information on
+ Internet Standards is available in Section 2 of RFC 5741.
+
+ Information about the current status of this document, any errata,
+ and how to provide feedback on it may be obtained at
+ http://www.rfc-editor.org/info/rfc6165.
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+Banerjee & Ward Standards Track [Page 1]
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+RFC 6165 Layer-2-IS-IS April 2011
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+Copyright Notice
+
+ Copyright (c) 2011 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) in effect on the date of
+ publication of this document. Please review these documents
+ carefully, as they describe your rights and restrictions with respect
+ to this document. Code Components extracted from this document must
+ include Simplified BSD License text as described in Section 4.e of
+ the Trust Legal Provisions and are provided without warranty as
+ described in the Simplified BSD 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 .....................................6
+
+1. Overview
+
+ There are a number of systems (for example, [RBRIDGES], [802.1aq],
+ and [OTV]) that use Layer-2 addresses carried in a link state routing
+ protocol, specifically Intermediate System to Intermediate System
+ [IS-IS] [RFC1195], to provide true Layer-2 routing. In almost all
+ the technologies mentioned above, classical Layer-2 packets are
+ encapsulated with an outer header. The outer header format varies
+ across all these technologies. This outer header is used to route
+ the encapsulated packets to their destination.
+
+ Each Intermediate System (IS) advertises one or more IS-IS Link State
+ Protocol Data Units (PDUs) with routing information. Each Link State
+ PDU (LSP) is composed of a fixed header and a number of tuples, each
+ consisting of a Type, a Length, and a Value. Such tuples are
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+Banerjee & Ward Standards Track [Page 2]
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+RFC 6165 Layer-2-IS-IS April 2011
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+ commonly known as TLVs. In this document, we specify a set of TLVs
+ to be added to [IS-IS] PDUs, to support these proposed systems. The
+ TLVs are generic Layer-2 additions, and specific ones, as needed, are
+ defined in the IS-IS technology-specific extensions. This document
+ does not propose any new forwarding mechanisms using this additional
+ information carried within 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 specifies the enhancements for the TLVs that are needed
+ in common by Layer-2 technologies.
+
+2.1. Multi-Topology-Aware Port Capability TLV
+
+ The Multi-Topology-aware Port Capability (MT-PORT-CAP) is IS-IS TLV
+ type 143 and has the following format:
+
+ +-+-+-+-+-+-+-+-+
+ | Type=MTPORTCAP| (1 byte)
+ +-+-+-+-+-+-+-+-+
+ | Length | (1 byte)
+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+ |R|R|R|R| Topology Identifier | (2 bytes)
+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+ | sub-TLVs (variable bytes) |
+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+
+ o Type: TLV Type, set to MT-PORT-CAP TLV 143.
+
+ o Length: Total number of bytes contained in the value field,
+ including the length of the sub-TLVs carried in this TLV.
+
+ o R: Reserved 4 bits, MUST be sent as zero and ignored on receipt.
+
+ o Topology Identifier: MT ID is a 12-bit field containing the MT ID
+ of the topology being announced. This field when set to zero
+ implies that it is being used to carry base topology information.
+
+ o Sub-TLVs: The MT-PORT-CAP TLV value contains sub-TLVs formatted as
+ described in [RFC5305]. They are defined in the technology-
+ specific documents.
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+RFC 6165 Layer-2-IS-IS April 2011
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+ The MT-PORT-CAP TLV may occur multiple times and is carried within 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 has the
+ following format:
+
+ +-+-+-+-+-+-+-+-+
+ | 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) |
+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-...+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+
+ o Type: TLV Type, set to 147 (MAC-RI).
+
+ o Length: Total number of bytes contained in the value field given
+ by 5 + 6*n bytes.
+
+ o Topology-id/Nickname : Depending on the technology in which it is
+ used, this carries the topology-id or nickname. When this field
+ is set to zero, this implies that the Media Access Control (MAC)
+ addresses are reachable across all topologies or across all
+ nicknames of the originating IS.
+
+ o Confidence: This carries an 8-bit quantity indicating the
+ confidence level in the MAC addresses being transported. Whether
+ this field is used, and its semantics if used, are further defined
+ by the specific protocol using Layer-2 IS-IS. If not used, it
+ MUST be set to zero on transmission and be ignored on receipt.
+
+ o RESV: (4 bits) MUST be sent as zero and ignored on receipt.
+
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+ o VLAN-ID: This carries a 12-bit VLAN identifier that is valid for
+ all subsequent MAC addresses in this TLV, or the value zero if no
+ VLAN is specified.
+
+ o MAC(i): This is the 48-bit MAC address reachable from the IS that
+ is announcing this TLV.
+
+ The MAC-RI TLV is carried in a standard Link State PDU (LSP). This
+ TLV can be carried multiple times in an LSP and in multiple LSPs. It
+ MUST contain only unicast addresses. The manner in which these TLVs
+ are generated by the various Layer-2 routing technologies and the
+ manner in which they are consumed are detailed in the technology-
+ specific documents.
+
+ In most of the technologies, these MAC-RI TLVs will translate to
+ populating the hardware with these entries and with appropriate next-
+ hop information as derived from the advertising IS.
+
+3. Acknowledgements
+
+ The authors would like to thank Peter Ashwood-Smith, Donald E.
+ Eastlake 3rd, Dino Farinacci, Don Fedyk, Les Ginsberg, Radia Perlman,
+ Mike Shand, and Russ White for their useful comments.
+
+4. Security Considerations
+
+ This document adds no additional security risks to IS-IS, nor does it
+ provide any additional security for IS-IS.
+
+5. IANA Considerations
+
+ This document specifies the definition of a set of new IS-IS TLVs --
+ the Port-Capability TLV (type 143) and the MAC-Reachability TLV
+ (type 147). They are listed in the IS-IS TLV codepoint registry.
+
+ IIH LSP SNP
+ MT-Port-Cap-TLV (143) X - -
+ MAC-RI TLV (147) - X -
+
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+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.
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+Banerjee & Ward Standards Track [Page 6]
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+RFC 6165 Layer-2-IS-IS April 2011
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+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
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