Hi Rain,
> On Aug 6, 2025, at 3:25 AM, rain_alex via lists.fd.io > <wangdaobei=gmail....@lists.fd.io> wrote: > > Source port allocation is assigned by the transport layer, My concurrency is > very high, so port duplication is normal. > > Nginx actively closed the connection. > > The process is as follows: > nginx: fin, seq=100, ack=200 > vpp: fin ack:seq=200 ack=101 > nginx: seq=101 ack= 201 > > after 10 seconds: > vpp: syn: seq =10 ack = 0 > nginx: syn=101 ack=201 > > 2msl time equals 1s has been set. > > So what you mean is that the 2msl time has not taken effect, and in the same > 5-tuple, the sequence number of the next syn request generated within > time_wait time needs to be greater than the previous one ? Exactly, but modulo arithmetic greater, not just greater number. > But in same 5-tuple, some packages have smaller syn than the previous stream, > and nginx still responds normally . Can you do a comparison of the two raw seq number values like the one done by seg_gt macro in tcp_packet.h? If if turns out this is not the issue, it may be that linux is not yet in time-wait state, i.e., closing handshake did not complete successfully and probably some of the timeouts in vpp are shorter than the ones in linux. Regards, Florin > > Regards, > Rain > > >
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