Local multihomed source S2 on a pair of MEG or PEG PE1 and PE2, BD2

Figure: Local multihomed sources shows a scenario where PE1 and PE2 are multihomed to a local source. A local receiver is also using multihoming to the same MEG or PEG pair. PE2 is the SBD-DR.

When the source sends multicast traffic for S2,G2, VXLAN local-bias or regular ESI-label filtering ensures the multihomed local receiver does not get duplicate traffic. The following applies in this scenario:

• The MEG SBD-DR (PE2) still performs the FHR functionality in this case (sends register/Source A-D routes), even if the source was singlehomed to the non-DR.
• If S2 was singlehomed to PE2 only, to avoid tromboning, the source S2 would be learned via ARP/ND as a host route and advertised in a VPN-IP route to attract the join route on PE2.
• If S2 is multihomed, as shown in Figure: Local multihomed sources, tromboning may occur, but traffic still flows correctly. For example:
  1. the remote PE performs UMH selection and picks up PE1
  2. PE1 generates a SMET route in the SBD as usual
  3. the SMET is imported and the state added to BD2 in PE2
  4. traffic is received by PE2, forwarded to PE1 via BD2, and then forwarded to the remote MVPN/PIM PE