Segmented Multicast Stitching With Inter-As Solution; Configuring Segmented Multicast Stitching - Cisco ASR 9000 Series Configuration Manual

Implementing Layer-3 Multicast Routing on Cisco IOS XR Software

Segmented Multicast Stitching with inter-AS Solution

The segmented multicast stitching with inter-AS solution ensures that the ABR and ASBR having an incoming
core type is switched to a different or same core type. iABR is the tail for the P2MP/mLDP tree of the ingress
non-zero area, however, it can be a bud for the P2MP/mLDP tree on the ingress ASBR. The ingress LC
decapsulates the incoming packet, and the encapsulated ID model is used to encapsulate the packet with the
egress core type. When the egress core type is P2MP, the incoming label is replaced with the head local label
of the outgoing P2MP core.
In the case where there are label receivers for the same core, the ingress LC creates two copies - one for the
bud case and the other for encapsulation of the next core. The impact of sending two copies to the fabric will
be similar to that of other existing implementations such as IRB and PBB-EVPN.
Working of Segmented Multicast Stitching
The working of the Segmented Multicast stitching is explained in the following steps:
1 iABR is the tail for the P2MP/MLDP tree of the ingress non-zero area. Similarly, eABR is the tail for the
P2MP/MLDP tree of the zero-area core. At the iABR tail node's ingress LC, the encapsulation ID of the
core zero area tree is downloaded.
2 The incoming label lookup on the tail node indicates that this is a stitching case, and decapsulates, and
picks up the tunnel label/encapsulation ID of the next segment and initiate forwarding on to the next core
type.
3 In the case of a bud scenario, the ingress LC at the ABR creates two copies when the incoming label
indicates the need for stitching. One copy is used for stitching, and the other copy for regular bud node
forwarding. For the bud scenario, 2 sets of (FGID, MGID) is required
• one for the stitching
• other for regular bud node forwarding
4 Control packets: PIM packets are exchanged between iPE and ePE. BGP packets are exchanged between
iPE/iABR, iABR/eABR, and eABR/ePE.
5 OAM packets: OAM packets are placed on the incoming core and stitched across to the next core.

Configuring Segmented Multicast Stitching

You must configure segmented color on the PEs and optionally segment-border route policy on the
ABRs/ASBRs for Segmented Multicast. When the segment-border router policy is not configured, the
downstream core inherits the core type of the upstream core.
Cisco ASR 9000 Series Aggregation Services Router Multicast Configuration Guide, Release 6.0.x
Segmented Multicast - Overview
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