[ns] Is FTP traffic over TCP connection uses always the same route?

[Dr. Mohamed Ben Othman]

Hi,

 

Thank you all for your answers. Some asked me which protocol I am using. I
am using the default protocol (IP). But what I still not sure about is that:
in the reality (in the field) is data has to pass through the same path
(route) from src to dst because TCP is a connection oriented protocol. What
I was thinking is that over a TCP connection the src has to ask for a
session and cannot send data until the dst accepts but there is no way to
fix the path. Am I wrong? If this is not true how this path is guaranteed
within the different routers and what will happen if the routing table of a
router in the middle of the path changes (by removing the path going to the
dst).

 

On the other hand and if I am thinking right is there how to reflect this
using NS.

 

Some told me that the NS chooses the shortest path. By saying this is the
shortest path is only minimum number of hops or also minimum loaded path.

 

Thank you very much.

Mohamed Ben Othman.

 

 

  _____  

From: Vijay Ghorpade [mailto:vijayghorpade at rediffmail.com] 
Sent: Thursday, February 15, 2007 12:08 AM
To: Dr.Mohamed Ben Othman
Subject: Re: [ns] Is FTP traffic over TCP connection uses always the same
route?

 

Dear Sir,
  Basically TCP is a connection oriented protocol so ns will establish a
connection between a src and dst first and then sends the packets. From your
topology it is clear that there are two paths src-r1-r2-r4-dst and
src-r1-r3-r4-dst. It seems that the cost of both the paths is equal. Hence
it is choosing any one path.
You can try by changing the cost of the path.

Vijay
  


On Tue, 13 Feb 2007 Dr.Mohamed Ben Othman wrote :
>
>Dear all,
>
>
>
>I have a topology of 6 nodes: a src, dst and 4 connected routers:
>
>Src connected to r1
>
>Dst connected to r4
>
>
>
>r1 connected to r2 and r3
>
>r2 connected to r4
>
>r3 connected to r4
>
>
>
>            Src ---- r1 --------r2
>
>                        |          |
>
>                        R3-------r4-------dst
>
>
>
>I sent traffic from src to dst and monitored the different queues. The
>problem is that the traffic always passes through r1, r2 and then r4.
>
>The queue of r3 is always empty.
>
>I tried to modify the queues sizes, the delay etc but I didn't succeed.
>
>I thought that TCP connection may take more than one route and the traffic
>passes via all possible routes.
>
>Can anyone help me.
>
>Thank you.
>
>Mohamed ben Othman
>
>
>



 
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