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Re: [ns] tcp-full agent runs error with wireless-cum-wired mip ,help!
On Thu, 26 Jul 2001 [email protected] wrote:
> Hi,all:
> When I ran FullTcpAgent in mobile ip scenario,the following error
> occurs:
> 20.021528: FullTcpAgent::recv(_o175) got packet lacking ACK (seq
> 21)
> Would anyone help me? Thanks.
>
> Yiying,Chen
> Beijing University of Posts & Telecommunications, China
I've gotten this error message when the server's SYN/ACK is lost and the
client resends its SYN. The server is in SYN_RECEIVED state and then
receives a duplicate SYN. I fixed my problem by only printing this error
message when (state_ != TCPS_SYN_RECEIVED). The appropriate behavior (in
my opinion) is to just ignore the resent SYN. The server will resend the
SYN/ACK in a short time anyway, due to its timeout mechanism. Anyone have
other ideas of what should happen in this case?
In what I described above, the sequence number reported in the error
message is 1, but you're getting 21, so there may be a different problem.
I'd suggest printing the current TCP state when this error occurs (the
code is in tcp-full.cc).
Michele
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Michele C. Weigle
[email protected], [email protected]
http://www.cs.unc.edu/~clark
CB# 3175, Sitterson Hall
Department of Computer Science
University of North Carolina
Chapel Hill, NC 27599-3175
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