Why it takes a long time to connect(TCP) in this condition ?

Two Linux machines: embedded ( client ) and Ubuntu ( server ).
Everything works fine If the server is UP and listening when the
client tries to connect.
But if the server is not UP yet, then the client calls connect, it
fails ( which is OK ), but then I sleep(1) and try to connect again.
Then I start the server and I would expect the next connect call to
work fine, but it does not, it keeps failing for a while and then
after
a looooong time ( 30s or so ) it works.
I have capture the packets, I am not sure if I should post it here
and in what format, I can see that after the server is UP, SYN ACKs
are sent back from the server to the client, but the client just keep
seending more SYNs.

Thanks is advance for any comments.

(E-Mail Removed) wrote:
> Two Linux machines: embedded ( client ) and Ubuntu ( server ).
> Everything works fine If the server is UP and listening when the
> client tries to connect.
> But if the server is not UP yet, then the client calls connect, it
> fails ( which is OK ), but then I sleep(1) and try to connect again.
> Then I start the server and I would expect the next connect call to
> work fine, but it does not, it keeps failing for a while and then
> after
> a looooong time ( 30s or so ) it works.
> I have capture the packets, I am not sure if I should post it here
> and in what format, I can see that after the server is UP, SYN ACKs
> are sent back from the server to the client, but the client just keep
> seending more SYNs.
>

are the tcp isn numbers correct ?
seems like a complete tcp connection isn't established
correctly

> Thanks is advance for any comments.

Can u post those packets what ever u have captured. I can help u if u
provide those packets. And whenever ur server/client is down then
obviously connection to that machine fails.

- A_A_K

On Mar 12, 4:16*am, A_A_K <401a...@gmail.com> wrote:
> Can u post those packets what ever u have captured. I can help u if u
> provide those packets. And whenever ur server/client is down then
> obviously connection to that machine fails.
>
> - A_A_K

Thanks for the help. I would like to hold on on this issue until I can
clarify something,
it looks like my physical layer is not working well ( Ethernet over
USB ), I repeated the same
test on real Ethernet and it worked fine, and I am already suspicious
of this physical layer.
So sorry for posting this issue without checking the physical layer,
but I may return here
if the physical layer is working fine.
Thanks!

On Mar 12, 2:39*am, "goarilla@work" <kevindotpau...@mtmdotkuleuven.be>
wrote:
> joseluismarche...@yahoo.com.br wrote:
> > Two Linux machines: embedded ( client ) and Ubuntu ( server ).
> > Everything works fine If the server is UP and listening when the
> > client tries to connect.
> > But if the server is not UP yet, then the client calls connect, it
> > fails ( which is OK ), but then I sleep(1) and try to connect again.
> > Then I start the server and I would expect the next connect call to
> > work fine, but it does not, it keeps failing for a while and then
> > after
> > a looooong time ( 30s or so ) it works.
> > I have capture the packets, I am not sure if I should post it here
> > and in what format, I can see that after the server is UP, SYN ACKs
> > are sent back from the server to the client, but the client just keep
> > seending more SYNs.
>
> are the tcp isn numbers correct ?
> seems like a complete tcp connection isn't established
> correctly
>
> > Thanks is advance for any comments.

Thanks for the help. I would like to hold on on this issue until I can
clarify something,
it looks like my physical layer is not working well ( Ethernet over
USB ), I repeated the same
test on real Ethernet and it worked fine, and I am already suspicious
of this physical layer.
So sorry for posting this issue without checking the physical layer,
but I may return here
if the physical layer is working fine.
Thanks!