[ns] Re: FullTcp with satellites network,

[Lloyd Wood <l.wood@eim.surrey.ac.uk>]

On Thu, 24 Feb 2000, Alioune THIAM wrote:
> 
> Did anybody know why FullTcp don't work correctly with the Satellites
> network ? I am trying to build a simulation like that provided in
> sat-teledesic.tcl by changing the the udp agent with a FullTcp but there
> always an error like : FullTcp::recv(_0345) Bad ack(21) to my Syn(1).
>                        FullTcp::recv(_0346) god packet lacking ack(21).

I've found that commenting out the line

		cmh->size() += IP_HDR_LEN;

in satroute.cc (added for simulating IP-in-IP tunnelling throughout?)
fixes this and allows FullTcp to work.

ns is generally unclear about distinguishing between headers and
payload sizes; FullTcp is using subtraction to check payload size in
the initial SYN/ACK exchange, and gets caught by this addition.

L.

<L.Wood@surrey.ac.uk>PGP<http://www.ee.surrey.ac.uk/Personal/L.Wood/>