3com 3031 Instruccion De Instalación

This chapter covers the following topics:

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MPLS (Multiprotocol Label Switching) encapsulates packets with labels of short 
and fixed length. MPLS obtains service from various link layers (such as PPP, ATM, 
Frame Relay, Ethernet and etc.) and provides connection-oriented services for 
network layer. MPLS can obtain support from IP routing protocol, control protocol 
and at the same time, it supports policy-based restraint route. It possesses 
powerful and flexible routing functions and is capable of satisfying requirements 
for the network from various new applications. This technology originated from 
IPV4. However, its core technology can be extended to multiple network protocols 
(IPV6, IPX, etc). 

MPLS is a protocol initially put forward for increasing forwarding speed of routers. 
However, its application is not limited only to this due to its many advantages. It is 
also widely used in VPN, QoS and it is increasingly becoming an important 
standard for large-scale IP network. 

Forwarding Equivalent Class (FEC), in fact, is 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 for example) 
into one group, which is called a FEC. The FEC classification is based on the 
network layer address. Packets in the same FEC will be processed in absolutely the 
same way.

Label definition  Label is a locally significant and short identifier with fixed 
length, which is used to identify a particular FEC. When reaching at MPLS network 
ingress, packets are divided into different FECs, on which different labels are 
encapsulated. Subsequent forwarding is based on these labels.