Bgp Requirements; Segmented Multicast - Overview - Cisco ASR 9000 Series Configuration Manual

Implementing Layer-3 Multicast Routing on Cisco IOS XR Software
mdt default ipv4 226.8.0.1
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address-family ipv6
mdt data 226.8.4.0/24 threshold 5
mdt default ipv4 226.8.0.1
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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 ASR 9000 Series Aggregation
Services Router Routing Configuration Guide for information on BGP support for Multicast VPN.

Segmented Multicast - Overview

IOS-XR supports the NextGen (NG) Multicast VPNs with BGP (Border Gateway Protocol) MVPN SAFI
(Sub AFI). NextGen MVPN defines a set of auto-discovery and C-multicast Route types that supports different
MVPN features. The set of standards that extend MVPN-SAFI for Global Table Multicast (GTM) and to
support MVPN in the presence of Segmented Cores is called as Segmented Multicast.
In Segmented Core MVPN, the Layer-3 VPN core or the GTM core is divided into multiple Segments. These
segments can be multiple OSPF areas, Intermediate System - Intermediate System (IS-IS) levels, or multiple
IGP instances, within an Autonomous System (AS) or across multiple ASes. Multicast core-trees are generally
built from Ingress-PE to Egress-PE. With Segmented cores, separate multicast trees are present in each
segment, and the border routers stitch the multicast trees between segments.
Border router refers to an Area Border Router (ABR) or an Autonomous System Border Router (ASBR). In
certain cases, the routers are the aggregation routers, connected to two segments in a network. These border
routers are attached to two Intra-AS segments. They may also be connected to ASBRs in other ASes at the
same time.
To support Segmented Core, BGP has to be enabled between the Provider Edge (PE) and the Border Routers,
and between the Border routers as well. BGP sessions are used to exchange Unicast routing information (for
sources, RPs, and so on) and MVPN SAFI. Unicast routing information is exchanged with either Multicast
SAFI (SAFI-2) or Unicast SAFI (SAFI-1) protocols.
The Segmented Core procedures change the way BGP A-D routes are sent between PEs. The C-multicast
Routes (Types 6 and 7) are unaffected and only required on the PEs. An additional support is provided to
facilitate the split behavior, where Types 1, 3, 4, 5 are to be sent from PEs to Border routers, while Types 6
and 7 are sent to a Service RR. The Service RR only peers with the PEs. This is achieved by adding the
Inter-Area Segmented NH EC (SNH-EC) to the A-D routes alone and having a BGP policy to announce or
block MVPN SAFI routes with and without SNH-ECs. Segmented Multicast and MVPNs are supported for
LSM trees only.
Cisco ASR 9000 Series Aggregation Services Router Multicast Configuration Guide, Release 6.0.x
Segmented Multicast - Overview
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