Hi Yacan, At this point, only ipv6 link local packets end up in ip-rewrite. Because of the v4/v6 symmetry we have arcs for both address families.
With respect to the two questions. First, tcp doesn’t cache the dpo for the remote ip because that would require tracking the dpo (in case it changes) and some of the apis involved are not thread safe. You can find some remnants of those attempts in tcp.c (eg tcp_connection_stack_on_fib_entry) although they’re compiled out and probably bit rotten at this point. Nonetheless, as you already found out, tcp-output can redirect packets to a custom node and provide some opaque context (next_node_opaque) but currently there are no apis for setting these two values. That is, the two are currently meant for vpp builtin applications that have access to the tcp connection. Does that fit your usecase? Otherwise, I am planning to add some apis that would allow vcl to change transport parameters soon. Regards, Florin > On Apr 7, 2021, at 1:56 AM, liuyacan <[email protected]> wrote: > > > Hi VPP experts, > > The command "show node tcp4-output" tell me that ip4-lookup and > ip4-rewrite > are both possible nodes for Tx packets. But I never saw the count of > ip4-rewrite > greater than zero.... > The function tcp_output_handle_packet() checks tc0's next_node_index > to > determine which node is appropriate, But I can not find any place that > modify > the filed.. > > My question is can tcp_connection_t store the FIB lookup result so that > subsequent > packets are able to bypass ip4-lookup node ? > > Best Regards, > Yacan > > > > > > > > > >
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