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VPN-A and VPN-B and forwards the packets. After receiving the packets from this source, PE2 and PE3
decapsulate and forward the packets to the respective MVRFs.
Figure 8: Receiver MVRF at the Source PE Router Receiver
For more information, see also
Configuring MVPN Extranet Routing, on page 119
and
Extranet Routing: Example, on page 160
.
RPF Policies in an Extranet
RPF policies can be configured in receiver VRFs to bypass RPF lookup in receiver VRFs and statically
propagate join states to specified source VRF. Such policies can be configured to pick a source VRF based
on either multicast group range, multicast source range, or RP address.
For more information about configuration of RFP policies in extranets, see
Receiver VRFs to Propagate Joins to a Source VRF: Example, on page 162
and
Receiver VRFs on Source PE Routers to Propagate Joins to a Source VRF: Example, on page 164
.
MVPN Bidirectional Overview
MVPN Bidirectional (BIDIR) uses GRE or MLDP MS-PMSI (Partitioned MDT) to support BIDIR in MVPN.
This functionality allows each RP-PE to announce a BGP AD route with a unique core group that is used by
the RP-PE for its partitioned MDT traffic. The core group is also configured and each PE that has the RP
mapping for the RP joins this group. All BIDIR sources are sending traffic to a group G along with encapsulated
source traffic as its own address. The group G of the partitioned-MDT corresponds to the correct RP-PE (the
PE via which the RP is reachable). Since there may be more than one partitioned-MDTs carrying traffic for
group G, receiver-PEs need to implement a strict RPF check based on the core group address G of the
partitioned-MDT.
The root of the partitioned-MDT (RP-PE) acts as the Designated Forwarders (DF) on its tree. BIDIR uses the
concept of Designated Forwarders (DF) for forwarding. A single DF for a particular PIM-BIDIR group exists
on every link within a PIM domain. DF is the router on the link with the best Unicast route to the RP.
Cisco IOS XR Multicast Configuration Guide for the Cisco CRS Router, Release 5.2.x
26
Implementing Multicast Routing on Cisco IOS XR Software
MVPN Bidirectional Overview