Re: [ns] Is FTP traffic over TCP connection uses always the same route?
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:[EMAIL PROTECTED] 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 http://adworks.rediff.com/cgi-bin/AdWorks/sigclick.cgi/www.rediff.com/signa ture-home.htm/[EMAIL PROTECTED]
Re: [ns] Is FTP traffic over TCP connection uses always the same route?
- You could define the routing protocol to use during the simulation, at the start of the tcl script with the $ns rtproto command. Then you could see what happens when changing the queue limits and sizes. NS, by default uses static routing with all routes pre-calculated before the start of the simulation and hence the traffic follows always the same route. In addition you could simulate a drop of one or more lines by using the dynamic models of NS and in that case if you use a dynamic routing protocol you will see the traffic changing route, while if not the traffic will experience a major packet drop at the precalculated intermediate node. -Fk On 2/14/07, [EMAIL PROTECTED] [EMAIL PROTECTED] wrote: -- Forwarded message -- From: Dr. Mohamed Ben Othman [EMAIL PROTECTED] To: ns-users@ISI.EDU Date: Tue, 13 Feb 2007 11:10:47 -0500 Subject: [ns] Is FTP traffic over TCP connection uses always the same route? 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 --===0022760753==-- ___ Ns-users mailing list Ns-users@isi.edu http://mailman.isi.edu/mailman/listinfo/ns-users -- Filippos N Kolovos Software Systems Analyst Engineer M.Sc. (Eng.) in Data Communications Automation Networking Department University of Macedonia Library Egnatia 156, P.O.Box 1591 540 06 Thessaloniki, Greece E-Mail: [EMAIL PROTECTED], [EMAIL PROTECTED] ---
[ns] Is FTP traffic over TCP connection uses always the same route?
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
