Bgp Requirements; Multitopology Routing - Cisco XR12000 Series Configuration Manual

Multitopology Routing

MDT-default group is configured on the PE router and is unique for each VPN. The PIM sends the join based
on the mode of the groups, which can be PIM SSM, or sparse mode.
Benefits of MVPN Inter-AS Support
The MVPN Inter-AS Support feature provides these benefits to service providers:
• Increased multicast coverage to customers that require multicast to span multiple services providers in
• The ability to consolidate an existing MVPN service with another MVPN service, as in the case of a
InterAS Option A
InterAS Option A is the basic Multicast VPN configuration option. In this option, the PE router partially plays
the Autonomous System Border Router (ASBR) role in each Autonomous System (AS). Such a PE router in
each AS is directly connected through multiple VRF bearing subinterfaces. MPLS label distribution protocol
need not run between these InterAS peering PE routers. However, an IGP or BGP protocol can be used for
route distribution under the VRF.
The Option A model assumes direct connectivity between PE routers of different autonomous systems. The
PE routers are attached by multiple physical or logical interfaces, each of which is associated with a given
VPN (through a VRF instance). Each PE router, therefore, treats the adjacent PE router like a customer edge
(CE) router. The standard Layer 3 MPLS VPN mechanisms are used for route redistribution with each
autonomous system; that is, the PEs use exterior BGP (eBGP) to distribute unlabeled IPv4 addresses to each
other.
Option A allows service providers to isolate each autonomous system from the other. This provides better
Note
control over routing exchanges and security between the two networks. However, Option A is considered
the least scalable of all the inter-AS connectivity options.

BGP Requirements

PE routers are the only routers that need to be MVPN-aware and able to signal remote PEs with information
regarding the MVPN. It is fundamental that all PE routers have a BGP relationship with each other, either
directly or through a route reflector, because the PE routers use the BGP peering address information to derive
the RPF PE peer within a given VRF.
PIM-SSM MDT tunnels cannot be set up without a configured BGP MDT address-family, because you
establish the tunnels, using the BGP connector attribute.
See the Implementing BGP on Cisco IOS XR Software module of the Cisco IOS XR Routing Configuration
Guide for the Cisco XR 12000 Series Router for information on BGP support for Multicast VPN.
Multitopology Routing
Multitopology routing allows you to manipulate network traffic flow when desirable (for example, to broadcast
duplicate video streams) to flow over non-overlapping paths.
Cisco IOS XR Multicast Configuration Guide for the Cisco XR12000 Series Router, Release 5.1.x
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an MPLS Layer 3 VPN service.
company merger or acquisition.
Implementing Multicast Routing on Cisco IOS XR Software
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