RFC 3034 (rfc3034) - Page 2 of 24

Use of Label Switching on Frame Relay Networks Specification

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RFC 3034            Label Switching with Frame Relay        January 2001


   5.6  Label Processing by Core FR-LSRs.........................12
   5.7  Label Processing by Egress FR-LSRs.......................13
   6.  Label Switching Control Component for Frame Relay.........13
   6.1  Hybrid Switches (Ships in the Night)  ...................14
   7.  Label Allocation and Maintenance Procedures ..............15
   7.1  Edge LSR Behavior........................................15
   7.2  Efficient use of label space-Merging FR-LSRs.............18
   7.3  LDP message fields specific to Frame Relay...............19
   8.  Security Considerations  .................................21
   9.  Acknowledgments  .........................................21
   10. References  ..............................................22
   11. Authors' Addresses  ......................................23
   12. Full Copyright Statement  ................................24

1. Introduction

   The Multiprotocol Label Switching Architecture is described in
   [ARCH].  It is possible to use Frame Relay switches as Label
   Switching Routers.  Such Frame Relay switches run network layer
   routing algorithms (such as OSPF, IS-IS, etc.), and their forwarding
   is based on the results of these routing algorithms.  No specific
   Frame Relay routing is needed.

   When a Frame Relay switch is used for label switching, the top
   (current) label, on which forwarding decisions are based, is carried
   in the DLCI field of the Frame Relay data link layer header of a
   frame.  Additional information carried along with the top (current)
   label, but not processed by Frame Relay switching, along with other
   labels, if the packet is multiply labeled, are carried in the generic
   MPLS encapsulation defined in [STACK].

   Frame Relay permanent virtual circuits (PVCs) could be configured to
   carry label switching based traffic.  The DLCIs would be used as MPLS
   Labels and the Frame Relay switches would become Frame Relay Label
   Switching Routers, while the MPLS traffic would be encapsulated
   according to this specification, and would be forwarded based on
   network layer routing information.

   The keywords MUST, MUST NOT, MAY, OPTIONAL, REQUIRED, RECOMMENDED,
   SHALL, SHALL NOT, SHOULD, SHOULD NOT are to be interpreted as defined
   in RFC 2119.

   This document is a companion document to [STACK] and [ATM].








Conta, et al.               Standards Track
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