Re: Retransmission because of no ACK from user

[Martin Visser <martinvisser99 () gmail com>]

Is there an actual problem to be solved or are you just curious.
Retransmissions aren't all that unusual. If there is fluctuation in
round-trip-time as measured by TCP, then the TCP retransmission timer
might expire more often than you would like. Hence you will get
retransmissions.

Regards, Martin

MartinVisser99 () gmail com



On 17 January 2011 18:12, vincent paul <amoteluro () yahoo com> wrote:
> Thank you for the response.  user did receive the packet twice.  This is the
> reason why wireshark label the second packet as retransmission.
>
> regards,
>
>
> ________________________________
> From: Andrew Hood <ajhood () fl net au>
> To: Community support list for Wireshark <wireshark-users () wireshark org>
> Sent: Sun, January 16, 2011 3:27:24 AM
> Subject: Re: [Wireshark-users] Retransmission because of no ACK from user
>
> vincent paul wrote:
> > Hi All,
> >
> > I am looking at one trace with retransmissions from server because user's
> > side
> > did not send ACK for packets it received from server.  Is there any reason
> > why
> > user's side does not send out ACK.
>
> Do you know the client did receive the data or is that an assumption?
>
> What is between the server and the client?
>
> Can you sniff the traffic at intermediate points?
>
> Do you see the session setup packets (SYN, SYN+ACK, ACK) and then when
> the data starts, the ACKs stop?
>
> This could be the classic "firewall dropping ICMP frag required packets"
> behaviour.
>
> Can you reduce the MTU at the server? In Windows you have to reduce it
> with a registry setting and that affects all interfaces and requires a
> reboot. Unixish systems let you set the MTU on route commands.
>
> If there is any ADSL involved, 1492 is a likely value for the MTU. 1460
> is the next most likely value.
>
> Andrew
> --
> There's no point in being grown up if you can't be childish sometimes.
>                 -- Dr. Who
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