Network Working Group A. Banerjee
Internet-Draft Cisco Systems
Intended status: Standards Track D. Ward
Expires: August 13, 2011 Juniper Networks
February 9, 2011
Extensions to IS-IS for Layer-2 Systems
draft-ietf-isis-layer2-11
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 Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79.
Internet-Drafts are working documents of the Internet Engineering
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Internet-Drafts are draft documents valid for a maximum of six months
and may be updated, replaced, or obsoleted by other documents at any
time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as "work in progress."
This Internet-Draft will expire on August 13, 2011.
Copyright Notice
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document authors. All rights reserved.
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publication of this document. Please review these documents
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carefully, as they describe your rights and restrictions with respect
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Table of Contents
1. Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
1.1. Terminology . . . . . . . . . . . . . . . . . . . . . . . 3
2. TLV Enhancements to IS-IS . . . . . . . . . . . . . . . . . . 4
2.1. Multi Topology aware Port Capability TLV . . . . . . . . . 4
2.2. The MAC-Reachability TLV . . . . . . . . . . . . . . . . . 4
3. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 7
4. Security Considerations . . . . . . . . . . . . . . . . . . . 8
5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 9
6. References . . . . . . . . . . . . . . . . . . . . . . . . . . 10
6.1. Normative References . . . . . . . . . . . . . . . . . . . 10
6.2. Informative References . . . . . . . . . . . . . . . . . . 10
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 11
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1. Overview
There are a number of systems (for example, [RBRIDGES], [802.1aq],
[OTV]) that use Layer-2 addresses carried in a link state routing
protocol, specifically Intermediate System to Intermediate System
(IS-IS) [IS-IS] [RFC 1195], 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
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 draft 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.
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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 an 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 [RFC 5305]. They are defined in the technology
scoped documents.
The MT-PORT-CAP TLV may occur multiple times, and is carried within a
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:
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+-+-+-+-+-+-+-+-+
| 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 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.
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
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manner 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 with appropriate next-hop
information as derived from the advertising IS.
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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.
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4. Security Considerations
This document adds no additional security risks to IS-IS, nor does it
provide any additional security for IS-IS.
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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) that needs to be reflected in the IS-IS TLV code-point
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 Exchange
Protocol for use in Conjunction with the Protocol for
Providing the Connectionless-mode Network Service (ISO
8473)", 2002.
[RFC 1195]
Callon, R., "Use of OSI IS-IS for Routing in TCP/IP and
Dual Environments", 1990.
[RFC 5305]
Li, T. and H. Smit, "IS-IS Extensions for Traffic
Engineering", 2008.
6.2. Informative References
[IEEE 802.1aq]
"Standard for Local and Metropolitan Area Networks /
Virtual Bridged Local Area Networks / Amendment 9:
Shortest Path Bridging, Draft IEEE P802.1aq/D1.5", 2008.
[OTV] Grover, H., Farinacci, D., and D. Rao, "OTV: Overlay
Transport Virtualization", draft-hasmit-otv-01, 2010.
[RBRIDGES]
Perlman, R., Eastlake, D., Dutt, D., Gai, S., and A.
Ghanwani, "RBridges: Base Protocol Specification", 2010.
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Authors' Addresses
Ayan Banerjee
Cisco Systems
170 W Tasman Drive
San Jose, CA 95138
US
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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