Multicast Over MLAG Configuration

Consider the following sample topology for MLAG:

DUT-1(core lic)======ISC vlan========DUT-2(core lic)

| |

+----------------DUT-3(edge lic)---------------+

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 MLAG config 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 vlan. DR node will send *,G and try to pull the traffic from RP. Non-DR does 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 will trigger the assert to avoid the traffic duplication. It is not recommended to setup RP on any vlan on MLAG peers.
  • It is best to avoid the assert operation since a small amount of traffic duplication happens during the this operation. You can avoid assert in some, but not all the scenarios.
  • DR priority configuration will help to make RP node as DR. (The DR priority feature is available from ExtremeXOS15.3.2 release onwards).
  • It is recommended that for PIM-SM deployments that the RP is configured on loopback VLANs instead of regular VLANs. This ensures continuous connectivity to the RP needing active ports present in that respective VLAN.