Re: [ns] packet type in the common header

["Alvaro Armenta" <aarmenta@cicese.mx>]

----- Original Message -----
From: "Sergio Andreozzi" <sergio.andreozzi@lut.fi>
To: "Alvaro Armenta" <aarmenta@cicese.mx>
Cc: "Ns-Users@Isi. Edu" <ns-users@isi.edu>
Sent: Tuesday, July 31, 2001 6:01 AM
Subject: RE: [ns] packet type in the common header


> > I changed the webtraffic packet type in the tcp-full.cc to HTTP
>
> I'm quite confused about the use of packet type field in the common packet
> header. Http application fills it with PT_TCP and telnet and ftp as well.
> Cbr traffic fills it has PT_CBR even if it uses udp agent. Realaudio uses
> PT_REALAUDIO and so on.
>
> In some case the transport protocol is used, in some other the application
> protocol or application type. Why not use two fields, one for application
> protocol, one other for transport protocol? It would be more clear.
>
> If I have a http server and a ftp agent on the same node, how can I
> distinguish packets? It seems port numbers are not used. Am I wrong?

There are two ways to doit (they are ugly, but they work for me :-) ).

1) As Web traffic uses tcp-full and ftp use TCP, and, if you are not using
other
application that is using tcp-full, you can mark all the packets generated
in
tcp-full.cc (as they all are webtraffic packets). Then you can separate
packets
using packet type (PT_FTP and PT_WEB) in your trace files.

2) Using flow_id. I reserve the first 2000 flows_id for the web traffic (as
web traffic
starts with flow_id = 0) and FTP to start at 3000 (to have a security band
to prevent flow_id
overlap). Then you can work on your trace file.

Alvaro
> Sergio
>
>
>
>