Mpls-Based Qos - 3Com 3C13636 Configuration Manual

3Com Router 3000 Ethernet Family
Configuration Guide
different branches of private network by using LSP, forming a united network.
MPLS-based VPN also supports the interconnection between different VPNs.
Branch 1 of
private network
Figure 1-6 MPLS-based VPN
The basic structure of MPLS-based VPN is shown in Figure 1-6. CE is the customer
edge device, and it may be a router, a switch, or perhaps a host. PE is a service
provider edge router, which is located on the backbone network. PE is responsible for
the management of VPN customers, establishing LSP connection between various
PEs, route allocation among different branches of the same VPN customer.
Usually the route allocation between PEs is realized by using extended BGP.
MPLS-based VPN supports the IP address multiplexing between different branches
and the interconnection between different VPNs. Compared with traditional route, it is
necessary to add branch and VPN distinguisher information in VPN route. Therefore, it
is necessary to extend BGP to carry VPN routing information.

1.6.2 MPLS-Based QoS

QoS is indispensable to the implementation of voice, video, and some other real-time
services over an IP network in the sense that it can differentiate the data streams so
that those crucial, sensitive, and delay-sensitive data streams over the network can be
processed first. As Huawei Technologies devices support MPLS-based Diff-serv
features, they can provide differentiated services for the data streams assigned with
different precedence levels while maintaining high network efficiency. Thus, they can
provide the services featuring guaranteed bandwidth, low delay, and low loss rate for
voice and video traffic. As it is difficult to deploy TE over the entire network, the Diff-ser
model is always preferred for implementing QoS in actual networking solutions.
The basic mechanism of Diff-serv goes like this: A service is mapped to a service
category, which can be uniquely identified by the DS bits in the TOS field of the IP
packets, according to the required service quality at the network edge. Then, the nodes
on the backbone network adopt the proper service policy to process the packets
according to the service category defined by the DS bits (derived from the TOS field),
ensuring the proper service quality. The service quality classification and the label
mechanism in Diff-serv are very similar to the label distribution in MPLS. In fact,
CE1 PE1
Backbone
network
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Chapter 1 MPLS Architecture
CE3
Branch 3 of
private network
PE3
CE2
private network
PE2
Branch 2 of