Should the one way and return route be the same? if not, then we talk about asymmetric routing. In some cases it’s advanteagous to have asymetric routing. In others, where firewalls per example, are put into play, symetric routing is more appropriate (return packets should use the established session opneing sat up by the initial packets)

In asymmetric routing, what is asymmetric? the processing of packets…

If the return packets flow the same way but in the opposite direction, we talk about symetric routing.