Port information for the neighbor learnt on port based router interfaces is directly known from the RIF's attachment id. Port information needs to be looked up from the L2 FDB for neighbors learnt on VLAN based router interface only. VLAN based router interface is used for inter-VLAN routing where packets are switched within the VLAN and L2 FDB will be populated for the switching.
Our understanding on why the port information is not designed as an attribute to the IP neighbor is that, there are ASICs where the pipeline model chains the L3 & L2 stages and the outgoing port is determined using L2 FDB lookup in the pipeline. So, determining port from the FDB entry should appear as the uniform model in SAI. Regards, Sathish From: opencompute-networking-boun...@lists.opencompute.org [mailto:opencompute-networking-boun...@lists.opencompute.org] On Behalf Of Mudigonda Mallik.Mlr Sent: Tuesday, August 04, 2015 6:53 PM To: opencompute-networking@lists.opencompute.org Subject: [Opencompute-networking] SAI Neighbor functionality - output port information Hi, The SAI v0.9.1 document has the following statement in Section 18 'Neighbor functionality'. "The IP neighbor does not define the outgoing port as this can be resolved using the FDB table." If the outgoing port of IP neighbor should be resolved by looking up the FDB table with the Destination Mac address, the FDB Table should also be populated with the Mac addresses learnt from the router interfaces as well. Generally, the FDB Table is populated with MAC addresses learnt from the bridge ports. A standard Arp entry or IPv6 Neighbor entry also specifies the outgoing interface. What is the reason for not including the outgoing port information as part of IP neighbor entry attributes? Thanks, Mallik
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