Procedures for SSM sources in OISM and receivers in MVPN

Irrespective of the DR election and source discovery process, when a MEG receives an MVPN C-multicast join route, it creates the Layer 3 multicast state and generates an SMET route for the S,G. This is shown in the following figure.

Figure 1. SSM sources in the EVPN network

• PE6 may pick PE4 as the Upstream Multicast Hop (UMH) PE for S1,G1 following regular MVPN procedures. In this case, PE4 adds the SBD interface as IIF, the MVPN tunnel as OIF member, and generates an SMET(S1,G1) route to draw the multicast traffic.

• Once PE4 creates state for (S1,G1), traffic to (S1,G1) is no longer sent to the CPM to be discarded, but it is forwarded in the data path based on the Layer 3 MFIB state.

• PE1 creates an MFIB for (S1,G1) and starts sending traffic to PE4. The following are two potential scenarios in this case.

  • If PE4 is configured as non-dr-attract-traffic false, it does not send the wildcard SMET. PE1 creates the following entries in the MFIB and sends traffic to both MEGs:
    • (*,*) oif: evpn-dest-PE3
    • (S1,G1) oif: evpn-dest-PE3, evpn-dest-PE4
  • If PE4 is configured as non-dr-attract-traffic true , PE4 and PE3 both send the wildcard SMET. PE1, ignores any SMET (S/*,G) routes from a PE when a SMET (*,*) is received from the same PE. If the (*,*) route is removed, PE1 reverts back to handling (S/*,G) entries. For this reason, PE1 in this case creates only (*,*) OIFs and sends the traffic to both MEGs.

    The following OIF entry is created: (*,*) oif: evpn-dest-PE3, evpn-dest-PE4.