topic Re: SDA anycast gateway in Software-Defined Access (SD-Access)

SDA anycast gateway

suya2024 — Wed, 17 Jul 2024 14:28:56 GMT

Hello,

I setup SDA fabric with two edge nodes 1 and 2. I have a PC connected to the same VN PROD on each edge node and can access resources on the external network. I shutdown the SVI for the VN PROD on one of the edge node and the PC connected to that edge node could no longer reach the external network as expected in traditional networks. What's the purpose of anycast gateway, if when an SVI is down on one edge node, the endpoints cannot use the anycast gateway on another edge node. Is this expected behavior in SDA fabric or my setup has some underlying issues?

Re: SDA anycast gateway

Torbjørn — Wed, 17 Jul 2024 17:54:03 GMT

The links between the nodes in an SDA fabric are (typically) routed, not switched. Your VLAN is hence not stretched beyond the local switch. The anycast gateway serves as the gateway only to the local switch. After frames are forwarded to your local AGW the local switch uses LISP to look up where the destination endpoint is. Once LISP finds the loopback address(RLOC) of the switch that has the destination attached, the local switch will encapsulate the frame in VXLAN and send it to the destination switch.

I am not able to find a good quick explanation of how Cisco SDA works at the moment. The CVD explains some of it, but I would really recommend reading the Cisco Press book Cisco Software Defined Access to get a good in-depth understanding of the solution.

Re: SDA anycast gateway

Andrii Oliinyk — Thu, 18 Jul 2024 07:27:13 GMT

just for better clarity: u shutdown SVI X on the EdgeNode Y, while SVI X remains UP on the EdgeNode Z, & PC connected to EdgeNode Z under SVY X loses connectivity?