Meaning if I have 2 links between site A and Site B and both are using cef per-destination load balance, will soure-destination pair used for load balance between site A and site B, will be the same as from Site B back to site A.. Or it might result Asymmetrical routing
Probably this is based on the cost of the paths. As I read from other posts, CEF populates FIB table by taking entries from routing table. So FIB will have interface against prefix, & this interface will be the 1 with the best cost to destination.
So if the pkt coming from interface doesnt have the best cost for return traffic then there may be case of asymetry.
But it does not cause any problems as per destination makes sure a flow is maintained via one link. So it could be quite possible to see that the originating session takes one route and the return traffic takes the other route
you can do a quick check on this by issuing the command
sh ip cef exact-route
try these commands on both ends for multiple source destination pairs and see whether they end up on the same link
HTH
Narayan
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