RFC 3035 (rfc3035) - Page 2 of 20
MPLS using LDP and ATM VC Switching
Alternative Format: Original Text Document
RFC 3035 MPLS using LDP and ATM VC Switching January 2001
Table of Contents
1 Introduction ........................................... 2
2 Specification of Requirements .......................... 3
3 Definitions ............................................ 3
4 Special Characteristics of ATM Switches ................ 4
5 Label Switching Control Component for ATM .............. 5
6 Hybrid Switches (Ships in the Night) ................... 5
7 Use of VPI/VCIs ....................................... 5
7.1 Direct Connections ..................................... 6
7.2 Connections via an ATM VP .............................. 7
7.3 Connections via an ATM SVC ............................. 7
8 Label Distribution and Maintenance Procedures .......... 7
8.1 Edge LSR Behavior ...................................... 8
8.2 Conventional ATM Switches (non-VC-merge) ............... 9
8.3 VC-merge-capable ATM Switches .......................... 11
9 Encapsulation .......................................... 12
10 TTL Manipulation ....................................... 13
11 Optional Loop Detection: Distributing Path Vectors ..... 15
11.1 When to Send Path Vectors Downstream ................... 15
11.2 When to Send Path Vectors Upstream ..................... 16
12 Security Considerations ................................ 17
13 Intellectual Property Considerations ................... 17
14 References ............................................. 18
15 Acknowledgments ........................................ 18
16 Authors' Addresses ..................................... 18
17 Full Copyright Statement ............................... 20
1. Introduction
The MPLS Architecture [1] discusses the way in which ATM switches may
be used as Label Switching Routers. The ATM switches run network
layer routing algorithms (such as OSPF, IS-IS, etc.), and their data
forwarding is based on the results of these routing algorithms. No
ATM-specific routing or addressing is needed. ATM switches used in
this way are known as ATM-LSRs.
This document extends and clarifies the relevant portions of [1] and
[2] by specifying in more detail the procedures which are to be used
for distributing labels to or from ATM-LSRs, when those labels
represent Forwarding Equivalence Classes (FECs, see [1]) for which
the routes are determined on a hop-by-hop basis by network layer
routing algorithms. The label distribution technique described here
is referred to in [1] as "downstream-on-demand". This label
distribution technique MUST be used by ATM-LSRs that are not capable
of "VC merge" (defined in section 3), and is OPTIONAL for ATM-LSRs
that are capable of VC merge.
Davie Standards Track