EVPN ESI BUM Forwarding

Thu Nov 17 21:29:05 UTC 2022

hey,

"The EVPN split-horizon procedure ensures that the BUM traffic 
originated by the multi-homed PE and sent from the non-DF to the DF, is 
not replicated back to the CE (echoed packets on the CE). To avoid these 
echoed packets, the non-DF (PE1) sends all the BUM packets to the DF 
(PE2) with an indication of the source Ethernet-Segment. That indication 
is the ESI Label (ESI2 in the example), previously signaled by PE2 in 
the AD per-ESI route for the Ethernet-Segment. When PE2 receives an EVPN 
packet (after the EVPN label lookup), the PE2 finds the ESI label that 
identifies its local Ethernet-Segment ESI2. The BUM packet is replicated 
to other local CEs but not to the ESI2 SAP."

https://datatracker.ietf.org/doc/html/draft-ietf-bess-evpn-mh-split-horizon

-- 
tarko