Re: emi2 response timeout handling

On Montag, November 25, 2002, at 09:37  Uhr, Christophe Teyssier wrote:

> On Friday 22 November 2002 20:02, Andreas Fink wrote:
>> The question is why does kannel not get an ACK on the connection?
>> UCP 60 is required when you open the session but you already have a
>> session. If it broke, then the TCP stream is closed and kannel detects
>> that and would reopen a new session with 60. Maybe there's a firewall
>> in the middle playing a bad game so you wont notice the TCP stream
>> being closed.
>
> I agree, this is not supposed to happen, but it is still a requirement 
> from
> Cegetel, and part of their test procedure (they won't let us connect 
> if we
> don't pass their tests).
>
> If the session is closed but the TCP connection is still there it 
> would be
> more logical to close it and start a new session on a new TCP 
> connection.

The point is that the session closing is exactly the same as TCP 
connection closing.
There's no UCP command saying "session closed". The session is open as 
long as the tcp connection is open so there's no sense to send any 60 
login command.

>  I  think this is quite likely to happen considering the number of 
> elements we're
> going through to get to them (Firewall/VPN/proxy).
>
> Maybe the solution is to use the keep-alive feature, what does kannel 
> do when
> it does not get an answer to a keepalive command? Is the TCP connection
> dropped?

Keepalive is in any case recommended for this kind of setup.
If I remember correctly a missing keepalive response would drop the 
connection from kannel's side and reconnect.


Andreas Fink
Global Networks, Inc.

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