HP FlexNetwork 7500 Series Configuration Manual page 202

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Multihop EBGP redistribution of labeled VPN-IPv4 routes between PE routers—PEs
advertise VPN-IPv4 routes to each other through MP-EBGP. This solution is also called
inter-AS option C.
For more information about the three inter-AS VPN solutions, see "Configuring MPLS L3VPN."
Based on these solutions, the following ways are available to implement inter-AS MD VPN:
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MD VPN inter-AS option A
•
MD VPN inter-AS option C
MD VPN inter-AS option A
As shown in
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Two VPN instances are in AS 1 and AS 2.
•
PE 3 and PE 4 are ASBRs for AS 1 and AS 2, respectively.
•
PE 3 and PE 4 are interconnected through their respective VPN instance and treat each other
as a CE device.
Figure 69 MD VPN inter-AS option A
To implement MD VPN inter-AS option A, a separate MD must be created in each AS. VPN multicast
data is transmitted between the VPNs in different ASs through the MDs.
A multicast packet of VPN instance 1 is delivered as follows:
CE 1 forwards the multicast packet of VPN instance 1 to PE 1.
1.
PE 1 encapsulates the multicast packet into a public network packet and forwards it to PE 3
2.
through the MTI interface in MD 1.
PE 3 treats PE 4 as a CE device of VPN instance 1, so PE 3 forwards the multicast packet to PE
3.
4.
PE 4 treats PE 3 as a CE device of VPN instance 2, so it forwards the multicast packet to PE 2
4.
through the MTI interface in MD 2 on the public network.
PE 2 forwards the multicast packet to CE 2.
5.
Because only VPN multicast data is forwarded between ASBRs, different PIM modes can run within
different ASs. However, the same PIM mode must run on all interfaces that belong to the same VPN
(including interfaces with VPN bindings on ASBRs).
MD VPN inter-AS option C
As shown in
•
A VPN network involves AS 1 and AS 2.
•
PE 3 and PE 4 are the ASBRs for AS 1 and AS 2, respectively.
•
PE 3 and PE 4 are interconnected through MP-EBGP and treat each other as a P device.
Figure 69:
Figure 70:
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