Quick Reference Guide

502 PowerConnect B-Series TI24X Configuration Guide
53-1002269-02
Multicast Source Discovery Protocol (MSDP)
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For PowerConnect B-Series TI24X devices, you must configure a fully meshed topology between
MSDP peers. This is mandated for this release beacuse of lack of any EGP that provides a peer RPF
check for SA messages that are forwarded between MSDP peers.
PIM Sparse routers use MSDP to register PIM Sparse multicast sources in a domain with the
Rendezvous Point (RP) for that domain.
Figure 89 shows an example of some PIM Sparse domains. For simplicity, this example shows only
one Designated Router (DR), one group source, and one receiver for the group. Only one PIM
Sparse router within each domain needs to run MSDP.
FIGURE 89 PIM Sparse domains joined by MSDP routers
In this example, the source for PIM Sparse multicast group 232.0.1.95 is in PIM Sparse domain 1.
The source sends a packet for the group to its directly attached DR. The DR sends a Group
Advertisement message for the group to the domain RP. The RP is configured for MSDP, which
enables the RP to exchange source information with other PIM Sparse domains by communicating
with RPs in other domains that are running MSDP.
Rendezvous Point (RP)
PIM Sparse Domain 3
Rendezvous Point (RP)
Receiver for
Group
232.1.0.95
PIM Sparse Domain 4
Rendezvous Point (RP)
PIM Sparse Domain 2
Source for
Group
232.1.0.95
PIM Sparse Domain 1
Designated Router (DR)
206.251.14.22
Source Advertisement message
1. DR receives traffic from source
and registers source with RP.
2. RP sends SA message
through MSDP to its MSDP
peers in other PIM Sparse
domains.
4. When SA caching is enabled,
the RP immediately responds to
Join messages from receivers.
Otherwise, the RP and receiver
must wait for the next SA message
for the group.
3. RP that receives the SA
floods the SA to all its MSDP
peers, except the one that sent
the SA.
Rendezvous Point (RP)
206.251.17.41