SDA ARP Handling

JUANNN — Sun, 12 Jul 2026 22:40:49 GMT

Hello, I am just trying to understand how ARP in the overlay is handled by SDA. I get all the operation an order of operations. But I have a doubt:

When the endpoint sends the ARP request and the Edge Node intercepts it, and then the Edge Node sends the MAP Request to retrieve the target MAC address from the Control Plane node (if present in it), the reply to this Map Request is not a common one (this is, the reply is not the remote RLOC). Instead, it's the MAC address of the target host.

So how does the CP know that this Map Request should be resolved using the Address Resolution table (show lisp instance-id L2IIDXXXX ethernet server address-resolution) rather than using the typical behavior?

Is it because the Map Request is sent targeting a tuple like (L2 IID (the one correspondednt to the VLAN where the ARP request came from), IP Address), rather than the typical tuples (L3 IID, IP Address) or (L2 IID, MAC Address)? So by receiving the "rare tuple" the CP knows that the lookup should be made in the AR Table?

And also, I see in some examples that the CP replies with the target MAC Address, and then a second Map Request is sent by the Edge Node to get the RLOC for the target MAC Address... why does the CP not put everything on a single Map Reply the first time?

Thanks!

topic SDA ARP Handling in Software-Defined Access (SD-Access)

SDA ARP Handling