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Fw: ns-questions
----- Original Message -----
From: Petra E. J. Napitu <[email protected]>
To: <[email protected]>
Sent: Monday, February 21, 2000 12:16 AM
Subject: ns-questions
> Dear Sir,
>
> Let me first introduce myself. My name is Petra and currently attending
> university. I have a research interest to investigate an explicit
congestion
> mechanism for TCP where the routers will send ICMP messages to the TCP
> sources. Correspondingly, the sources should react co-operatively to avoid
> congestion.
>
> So, I need to modify :
> 1. TCP source (cwnd modification)
> 2. RED at the router will generate ICMP packet (like the Source Quench)
>
> To investigate, I will use ns. My questions:
> 1. Will I need to make a new packet format for ICMP messages or there is a
> way to get around this (for example by modifying ecn-option) ? (The router
> will implement RED queue management and, when there is impending
congestion,
> accordingly GENERATE this ICMP-packets instead of marking or dropping the
> packet). The ICMP packet will contain the information of the congestion
> level.
>
> I realize that in ns, there is ecn-option which is echo-ed back by the TCP
> receiver through the ACKs, but I do not want this transport-level
mechanism
> to reduce the number of notification packets. I want the ICMP-packet to
> notify the sender (i believe there will be fewer control packets).
>
> It seems in ns TCP operates on unit of segment rather than IP-packets ?
>
> 2. I am new to ns (also to C++ and Otcl), I need your opinion on how
should
> I build my simulation
> a. If I modify TCP source (tcp. cc) and rename it to tcp_my.cc, how should
I
> indicate my Simulator to use the new agent ? Also, when I modify RED to
> generate packet instead of marking or dropping, what steps do I need to do
> after modifying red.cc?
> b. Should I re-compile ns ? What are the necessary changes ? Can I just
> embed the changes that I made to the current ns-binary ?
>
> Thank you kindly for your help.
> Yours,
> P. Napitu