Layer 3 IP Multicast using PIM-SM
Consider the following sample topology for MLAG:
DUT-1(core lic)======ISC vlan========DUT-2(core
DUT-1 and DUT-2 are MLAG peers, DUT-3 is a L2 switch whose uplink is a
LAG up to the pair of MLAG switches.
- RP and BSR can be configured on same device along with the MLAG
configuration, but we recommend to keep RP node away from MLAG peers. One MLAG peer will
be Designated Router (DR) and another one will be elected as NON-DR for MLAG
node will send *,G and try to pull the traffic from RP, and Non-DR will not pull the
traffic until DR is alive. If you config RP on Non-DR node then both MLAG peers will pull
the traffic which triggers the assert to avoid the traffic duplication. It is not
recommended to setup RP on any VLAN on MLAG peers.
- It is recommended to avoid the assert operation since a small amount of traffic duplication
happens during the assert operation. We can avoid assert in some scenario but not all the
- DR priority configuration will help to make RP node as DR. The DR priority feature is
available from 15.3.2 release onwards.
- It is recommended that for PIM-SM deployments, the RP is configured on
loopback VLANs instead of regular VLANs. This ensures continuous connectivity to the RP
without needing active ports present in that respective VLAN.
- It is recommended that for PIM-SM deployments, route-to-source must exist and receivers
should get the traffic from the SPT tree in the MLAG configurations. *,G forwarding in
MLAG is not a recommended configuration.