Asymmetric routing

Asymmetric routing in general is a normal, but unwanted situation in an IP network. Asymmetric routing is a situation where for one reason or another packets flowing in i.e. TCP connections flow through different routes to different directions. As a rough example: Host A and B located in different continents are communicating through a TCP connection. Segments sent from host A to host B reach the destination through WAN LINK X link but segments sent from B to A reach the destination through WAN LINK Y link.

ROUTERA----->WAN LINK X----->ROUTERB  Going  path.
ROUTERB----->WAN LINK Y----->ROUTERA  Return path.