How to keep the consistency of routing in multihoming environment?

[wjemail]

Does anyone have some idea on how to make sure the outbound/inbound route along the same path when connecting to 2 different ISPs?

Thanks and Regards,

Wang Jun

[Danilo Dy · Accepted solution]

Hi,

Be aware that ISP provisions asymmetric traffic flows (when outbound traffic goes out one link and returns via a different link). This is the internet norm.

In your local router connected to your upstream ISP, you can turn on CEF and apply "ip verify unicast reverse-path" in the incoming interface. Take note that this will or may drop packets that the best return path is not the inbound path.