Chapter 35 Mpls Architecture; Mpls Overview; Mpls Basic Concepts; Fec - 3Com 8800 Configuration Manual

3Com Switch 8800 Configuration Guide

Chapter 35 MPLS Architecture

Note:
A Switch 8800 running MPLS can serve as a router. Routers mentioned in this manual
can be either a router in common sense, or a layer 3 Ethernet switch running MPLS.
To enable MPLS function on the Switch 8800, you must select the interface cards that
support MPLS. Note that all the B cards do not support MPLS. For example, FT48C
card supports MPLS, but FT48B does not.

35.1 MPLS Overview

MPLS (Multiprotocol Label Switching) encapsulates network layer packets with short
and fixed-length labels. As the name implies, it supports multiple protocols, such as IP,
IPv6, and IPX. And it allows a device to make forwarding decision based on the labels
attached to the received packets without going through the complex routing table
lookup procedures with IP. MPLS brings together the advantages of the connectionless
control with IP and the connection-oriented forwarding with ATM. In addition to the
support from IP routing and control protocols, its powerful and flexible routing functions
allows it to accommodate to various emerging applications.
MPLS was initially proposed to accelerate the packet forwarding on routers, but it has
been widely used in Traffic Engineering (TE), Virtual Private Network (VPN), and other
aspects, and is becoming one of the most important standards on large scale IP
networks.

35.2 MPLS Basic Concepts

35.2.1 FEC

Forwarding Equivalence Class (FEC) is an important concept in MPLS. MPLS is
actually a kind of classify-and-forward technology. It categorizes packets with the same
forwarding strategy (same destination addresses, same forwarding routes and same
QoS levels) into one class, which is called a FEC. Generally, the FEC classification is
based on network layer address. Packets of the same FEC are processed in the same
way in MPLS network.
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Chapter 35 MPLS Architecture