Does anycast addressing, in itself, add any additional latency to network connections? Specifically, if you had two servers located in the same data center that had extremely similar routes/number of hops in route, up until the actual destination, one using unicast and the other using anycast, would there be any difference in latency between the two, noticeable or not?
It seems like having to look up the shortest route using BGP would have some sort of effect on latency, versus simply being able to use the one unicast address. I've been unable to find anything that mentions any additional overheard of using anycast addressing.
I also understand that if there was any additional overheard using anycast, it would probably be negligible in real world scenarios and that the benefits of anycast over unicast would still remain true.
Best Answer
No.
Anycast is unicast. It is just that the same network is in two different places, and the routing protocol chooses the closest network to which it send traffic destined for that network.
That is exactly what a router does. A routing protocol can receive multiple paths to a network, with or without anycast, but the router chooses one to place in the routing table, and it uses that one for traffic destined to that network. If the current route to that network in the routing table is lost, the next best path is automatically placed in the routing table and used.