Network Working Group Eric C. Rosen
Internet Draft Yakov Rekhter
Expiration Date: May 1998 Daniel Tappan
Dino Farinacci
Guy Fedorkow
Cisco Systems, Inc.
Tony Li
Juniper Networks, Inc.
Alex Conta
Lucent Technologies
November 1997
MPLS Label Stack Encoding on LAN Media
draft-rosen-mpls-lan-encaps-00.txt
Status of this Memo
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Abstract
''Multi-Protocol Label Switching (MPLS)'' [1,2,3] requires a set of
procedures for augmenting network layer packets with ''label stacks'',
thereby turning them into ''labeled packets'' [4]. Routers which
support MPLS are known as ''Label Switching Routers'', or ''LSRs''. In
order to transmit a labeled packet on a particular data link, an LSR
must support an encoding technique which, given a label stack and a
network layer packet, produces a labeled packet. This document
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specifies the encoding to be used by an LSR in order to transmit
labeled packets on LAN data links.
Table of Contents
1 Introduction ........................................... 2
1.1 Specification of Requirements .......................... 2
2 Transporting Labeled Packets over LAN Media ............ 3
3 Security Considerations ................................ 3
4 Authors' Addresses ..................................... 4
5 References ............................................. 5
1. Introduction
"Multi-Protocol Label Switching (MPLS)" [1,2,3] requires a set of
procedures for augmenting network layer packets with "label stacks",
thereby turning them into "labeled packets" [4]. Routers which
support MPLS are known as "Label Switching Routers", or "LSRs". In
order to transmit a labeled packet on a particular data link, an LSR
must support an encoding technique which, given a label stack and a
network layer packet, produces a labeled packet.
This document specifies the encoding to be used by an LSR in order to
transmit labeled packets on LAN data links.
1.1. Specification of Requirements
In this document, several words are used to signify the requirements
of the specification. These words are often capitalized.
MUST
This word, or the adjective "required", means that the
definition is an absolute requirement of the specification.
MUST NOT
This phrase means that the definition is an absolute prohibition
of the specification.
SHOULD
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This word, or the adjective "recommended", means that there may
exist valid reasons in particular circumstances to ignore this
item, but the full implications must be understood and carefully
weighed before choosing a different course.
MAY
This word, or the adjective "optional", means that this item is
one of an allowed set of alternatives. An implementation which
does not include this option MUST be prepared to interoperate
with another implementation which does include the option.
2. Transporting Labeled Packets over LAN Media
The label stack MUST be represented and processed as specified in
[4].
Each LAN frame that carries a labeled packet MUST carry exactly one
labeled packet.
The label stack entries MUST immediately precede the network layer
header, and MUST follow any data link layer headers, including, e.g.,
any VLAN headers, 802.1Q headers, etc. that may exist.
The ethertype value 8847 hex is used to indicate that a frame is
carrying an MPLS unicast packet.
The ethertype value 8848 hex is used to indicate that a frame is
carrying an MPLS multicast packet.
These ethertype values can be used with either the ethernet
encapsulation or the 802.3 SNAP/SAP encapsulation to carry labeled
packets.
The procedures for processing labeled packets are as specified in
[4].
3. Security Considerations
Security considerations are not discussed in this document.
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4. Authors' Addresses
Eric C. Rosen
Cisco Systems, Inc.
250 Apollo Drive
Chelmsford, MA, 01824
E-mail: erosen@cisco.com
Dan Tappan
Cisco Systems, Inc.
250 Apollo Drive
Chelmsford, MA, 01824
E-mail: tappan@cisco.com
Dino Farinacci
Cisco Systems, Inc.
170 Tasman Drive
San Jose, CA, 95134
E-mail: dino@cisco.com
Yakov Rekhter
Cisco Systems, Inc.
170 Tasman Drive
San Jose, CA, 95134
E-mail: yakov@cisco.com
Guy Fedorkow
Cisco Systems, Inc.
250 Apollo Drive
Chelmsford, MA, 01824
E-mail: fedorkow@cisco.com
Tony Li
Juniper Networks
3260 Jay Street
Santa Clara, CA 95051
E-mail: tli@jnx.com
Alex Conta
Lucent Technologies
300 Baker Avenue
Concord, MA, 01742
E-mail: aconta@lucent.com
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5. References
[1], "A Proposed Architecture for MPLS", 7/97, draft-ietf-mpls-arch-
00.txt, Rosen, Viswanathan, Callon
[2] "A Framework for Multiprotocol Label Switching", 7/97, draft-
ietf-mpls-framework-01.txt, Callon, Doolan, Feldman, Fredette,
Swallow, Visanathawan
[3] "Tag Switching Architecture - Overview", 7/97, draft-rekhter-
tagswitch-arch-01.txt, Rekhter, Davie, Katz, Rosen, Swallow
[4] "MPLS Label Stack Encoding", 11/97, draft-ietf-mpls-label-
encaps-00.txt, Rosen, Rekhter, Tappan, Farinacci, Fedorkow, Li,
Conta.
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