Ospf Vpn Extension - 3Com MSR 50 Series Configuration Manual

1476 C 79: MPLS L3VPN C
HAPTER
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OSPF VPN Extension

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ONFIGURATION
Figure 418 Recursion of HoPEs
UPE
CE
Figure 418 shows a three-level HoPE. The PE in the middle is called the
middle-level PE (MPE). MP-BGP runs between SPE and MPE, as well as between
MPE and UPE.
The term of MPE does not really exist in a HoVPN model. It is used here just for the
convenience of description.
MP-BGP advertises all the VPN routes of the UPEs to the SPEs, but advertises only
the default routes of the VPN instance of the SPEs to the UPEs.
The SPE maintains the VPN routes of all sites in the HoVPN, while each UPE
maintains only VPN routes of its directly connected sites. The number of routes
maintained by the MPE is between the above two.
This section focuses on the OSPF VPN extension. For more information about
OSPF, refer to the "OSPF Configuration" on page
OSPF multi-instance on PE
OSPF is a prevalent IGP protocol. In many cases, VPN clients are connected
through BGP peers, and the clients often run OSPF. Running OSPF between PEs
and CEs can simplify the configuration and management of the CEs, because the
CEs only need to support OSPF. In addition, if the customers require MPLS L3VPN
services through conventional OSPF backbone, using OSPF between PEs and CEs
can simplify the transition.
For OSPF to run between CEs and PEs, the PEs must support multiple OSPF
instances. Each OSPF instance must correspond to a VPN instance and have its
own interface and routing table.
The following describes details of OSPF configuration between PEs and CEs.
1 Configuration of OSPF areas between PEs and CEs
The OSPF area between a PE and a CE can be either a non-backbone area or a
backbone area.
SPE
MPE
UPE
UPE
CE
CE
CE
917.