[ns]bug in full-tcp: sequence number after duplicated ACKs

[Hyewon Jun <hyewon@cc.gatech.edu>]

hi,

I found a weird behavior and I would like to know what's happening.
I have a simple scenario:

There is one tcp connection between a server and a client to use ftp
application. In the middle of transmission, background traffic is added to
cause congestion to the link. After receiving 3 duplicated ACKs, the TCP
agent cut cwnd_ to half. So far so good.

but after that, TCP agent generates TCP packets having much smaller
sequence number. Not lost packet. (MSS=536)

seqno_ in TCP packet generated by the same TCP agent: 
   377345->15009->15545->increasing
t_seqno_ in TCP agent side: 
   378417 -> 378417 -> 378417 -> same
ack_ in TCP agent side :
   361801 - >361801 ->361801-> same

After receiving 35 duplicated ACKs, the tCP agent reduces cwnd_ into 1.
and the sequence number of tCP packets starts from -1:
   (25729)->(361801)-> -1->535->1071->1607->increasing
t_seqno_ in TCP agent side:
   (378417)->(378417)-> 362337 -> 362337 ->362337 ->362337-> ...
   -> same until receiving ack(362873: ACK for 361801)


Topology:

backtraffic -------------|
                         |
client------------------router--------------server    


Does anyone have similar experience?
If you have any idea what's causing this, would you please reply me?
Is it a bug in fulltcp?
I am using :ns-allinone-2.1b8a.

Thank you!
and Merry Christmas!
					
			-Hyewon Jun (hyewon@cc.gatech.edu)