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 This document is an Internet-Draft. Internet-Drafts are working documents of the Internet Engineering Task Force (IETF), its areas, and its working groups. Note that other groups may also distribute working documents as Internet-Drafts. 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." To learn the current status of any Internet-Draft, please check the "1id-abstracts.txt" listing contained in the Internet-Drafts Shadow Directories on ftp.is.co.za (Africa), nic.nordu.net (Europe), munnari.oz.au (Pacific Rim), ds.internic.net (US East Coast), or ftp.isi.edu (US West Coast). 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 Rosen, et al. [Page 1] Internet Draft draft-rosen-mpls-lan-encaps-00.txt November 1997 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 Rosen, et al. [Page 2] Internet Draft draft-rosen-mpls-lan-encaps-00.txt November 1997 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. Rosen, et al. [Page 3] Internet Draft draft-rosen-mpls-lan-encaps-00.txt November 1997 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 Rosen, et al. [Page 4] Internet Draft draft-rosen-mpls-lan-encaps-00.txt November 1997 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. Rosen, et al. [Page 5]