ECMP with DMAC Rewrite

Flow Offload Reference Pipeline User Guide (UG1670)

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1.1 English

ECMP with DMAC rewrite is a typical router function. ECMP enables routers to spread flows evenly leading to best utilization towards the destination. It also reduces congestion.

  • An ECMP table is used with an ecmp-id derived from flow-table lookup, to yield num_nexthops.
  • ECMP hashing is done as {flow_hash % num_nexthops} to pick the nexthop-id:
    • ECMP and nexthop-table entries are configurable via config.json.
    • There is support for deriving nexthop using nexthop_base.
  • Nexthop-table is used using nexthop-id to yield DMAC to be rewritten on the packet.