3Com 3C13636 Configuration Manual page 874

Router 3000 ethernet family

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3Com Router 3000 Ethernet Family

Configuration Guide

if the contained tag value is the same as that configured on PE during the route

calculation of OSPF process.

II. Multi-VPN-Instance CE

If supporting OSPF multi-instance, one router can run multiple OSPF procedures,

which can be bound to different VPN instances. In practice, you can create one OSPF

instance for each service type. OSPF multi-instance can fully isolate different services

in transmission, which can solve security problems with low cost. OSPF multi-instance

runs on PE router, which is called multi-VPN-instance CE. Currently, different services

in a LAN are often isolated with the VLAN function of a switch, but OSPF multi-instance

provides a solution for service isolation on routers.

Figure 3-7 Multi-VPN-instance CE application in conventional LAN

III. Sham Link

As shown in Figure 3-8,, two Sites in a same OSPF domain connect to PE1 and PE2.

There is an OSPF link inside the area (called backdoor link) between the two Sites. The

two Sides belong to a same VPN. In this case, the route connecting the two Sites

through PEs is called the Inter-Area Route. It is not selected as the optimal route by

OSPF because its preference is lower than that of the Intra-Area Route across the

backdoor link.

OSPF 200 VPN1

Figure 3-8 Sham link application

vpn-engineering

vpn-finances

MPLS VPN Backbone

3Com Corporation

Chapter 3 BGP/MPLS VPN Configuration

vpn-engineering

Multi-VPN-Instance CE

vpn-finances

OSPF 200 VPN1

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3c13636-us - router 3036 3000 series