[e2e] TCP losses

[Sireen Habib Malik]

Fred Baker wrote:

> At 10:54 AM 02/28/05 +0100, Sireen Habib Malik wrote:
>
>> How long does TCP take to decide that its connection has gone to the 
>> dogs and that the Application must do something about it? RFC1122 
>> (section 4.2.3.5) talks about "atleast" 100seconds. Is this applied 
>> practically?
>
>
> By some, yes, and often not. Practically, a routing outage lasting for 
> tens of seconds often results in TCP sessions failing. I'm not sure I 
> would peg it to 100 seconds nowadays, but some do seem a little brittle.
>
Thanks for the input.

>> At this point, i am interested in knowing what breaks TCP outside its 
>> own congestion related problems.  What are those failures? How 
>> frequently they occur? Any idea of duration?
>
>
> I would call those "loss-related", not "congestion-related". TCP only 
> sees congestion in the form of loss or variation in RTT.
>
got it.

>> It would be nicer, if the errors relevant for future large 
>> bandwidth-delay product IP over DWDM networks be given priority.
>
>
> I'm not sure I understand that statement. Are you asking responders to 
> think about DWDM (because it is interesting to you), or wondering 
> whether errors in a DWDM environment should be treated in some special 
> way by TCP, or what? 

Yes, IP over DWDM is my area of work and am interested in knowing what 
issues to consider.

To be more precise, i am simulating optical burst switching networks and 
congestion is one of the two thing that I have considered. All the rest 
of faults, i am simulating in a very crude manner by disrupting traffic 
for a X random time (presently deterministic). This way we can atleast 
study the impact of different protection and restoration on the 
application layer. I need more data to bring this crude-method closer to 
reality.

regards,
SM




-- 

Sireen Malik, M.Sc.
PhD. Candidate,

Communication Networks
Hamburg University of  Technology,
FSP 4-06 (room 3008)
Denickestr. 17
21073 Hamburg, Deutschland

Tel: +49 (40) 42-878-3387
Fax: +49 (40) 42-878-2941
E-Mail: s.malik at tuhh.de

--Everything should be as simple as possible, but no simpler (Albert Einstein)