4A0-D03: Nokia SR Linux EVPN and Data Center Interconnect

A Route Target is a BGP Extended Community used by EVPN to identify the applicable tenant and control route import and export. AFI/SAFI and the EVPN route type are protocol/NLRI identifiers, while a VXLAN Network Identifier is not the universal Extended Community value.

Learning a host MAC address in an L2 EVPN produces an EVPN Type 2 MAC/IP Advertisement route. EVPN Type 5 is an IP Prefix route used for Layer 3 prefix advertisement, not for advertising a newly learned Layer 2 host MAC address.

When a locally learned MAC entry ages out on a PE, the PE must withdraw that MAC address from BGP. EVPN MAC-mobility sequence numbers increase for a new local mobility event, while remote PEs use advertised routes rather than requiring MAC-table synchronization.

VXLAN encapsulates Layer 2 traffic over a Layer 3 underlay and uses a 24-bit VNI, allowing up to 16 million isolated overlay segments. UDP entropy can enable ECMP load sharing across underlay paths. EVPN is an optional BGP-based control plane used with VXLAN, rather than the purpose for which VXLAN was developed.

In an all-active EVPN Ethernet segment, exactly one designated forwarder (DF) forwards remotely received broadcast, unknown-unicast, and multicast (BUM) traffic to the multihomed device. Non-DF leafs do not forward that traffic toward the Ethernet segment, preventing duplicate BUM frames.