"just switching namespaces" isn't easy, since a packet (in the kernel represented by an SKB) has to have an interface it came in on. The main role an veth pair

"just switching namespaces" isn't easy, since a packet (in the kernel represented by an SKB) has to have an interface it came in on. The main role an veth pair has is to move the packet between namespaces, and to provide a new in interface, one that is visible in the new namespace. Unless someone did something crazy, traversing a veth pair should just be doing a little bookkeeping on the SKB, no data copies at all.