Chapter 1 Mpls Architecture; Mpls Overview; Mpls Basic Concepts; Fec - H3C S9500 Series Operation Manual

Operation Manual – MPLS
H3C S9500 Series Routing Switches

Chapter 1 MPLS Architecture

Note:
The H3C S9500 Series Routing Switches (hereinafter referred to as S9500 series)
running MPLS can serve as routers. Routers mentioned in this manual can be either a
router in common sense, or a layer 3 Ethernet switch running MPLS.
For S9500 switches, only the interface boards with the suffixes C, CA and CB and
VPLS service processor cards support the MPLS function. To enable MPLS function on
the S9500 switches, you must select the interface cards that support MPLS or VPLS
service processor cards. The suffix of a board can be identified through the silkscreen
on the upper right corner of the front panel of the card. For example, the silkscreen on
LSB1GP12B0 card is GP12B, so the suffix of the card is B.

1.1 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.

1.2 MPLS Basic Concepts

1.2.1 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
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Chapter 1 MPLS Architecture