Mpls L3Vpn Routing Information Advertisement - 3Com MSR 50 Series Configuration Manual

MPLS L3VPN Routing
Information
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Figure 410 Network diagram for extranet networking scheme
VPN 1
VPN 1:
Import:100:1
Site 1
Export:100:1
CE
CE
Site 2
VPN 1
In Figure 410, VPN 1 and VPN 2 can access Site 3 of VPN 1.
PE 3 can receive the VPN-IPv4 routes advertised by PE 1 and PE 2.
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PE 1 and PE 2 can receive the VPN-IPv4 routes advertised by PE 3.
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Based on the above, Site 1 and Site 3 of VPN 1 can communicate with each
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other, and Site 2 of VPN 2 and Site 3 of VPN 1 can communicate with each
other.
PE 3 advertises neither the VPN-IPv4 routes received from PE 1 to PE 2, nor the
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VPN-IPv4 routes received from PE 2 to PE 1 (that is, routes learned from an IBGP
neighbor will not be advertised to any other IBGP neighbor). Therefore, Site 1
of VPN 1 and Site 2 of VPN 2 cannot communicate with each other.
In basic MPLS L3VPN networking, the advertisement of VPN routing information
involves CEs and PEs. A P router maintains only the routes of the backbone and
does not need to know any VPN routing information. A PE maintains only the
routing information of the VPNs directly connected to it, rather than that of all
VPNs. Therefore, MPLS L3VPN has excellent scalability.
The VPN routing information of a local CE is advertised in three phases:
1 Advertised from the local CE to the ingress PE.
2 Advertised from the ingress PE to the egress PE.
3 Advertised from the egress PE to the remote CE.
Then, a route is available between the local CE and the remote CE, and the VPN
routing information can be advertised on the backbone.
The following describes these phases in detail.
PE 1
PE 2
VPN 2:
Import:200:1
Export:200:1
MPLS L3VPN Overview
VPN 1
PE 3
Site 3
VPN 1:
Import:100:1,200:1
Export:100:1,200:1
1467
CE