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[SCTP-Discussion] Problem with SCTP_setPrimary()


Chronological Thread 
  • From: Le Vinh Dat <vinhdat82 AT yahoo.com>
  • To: Michael Tuexen <Michael.Tuexen AT micmac.franken.de>
  • Cc: discussion AT sctp.de
  • Subject: [SCTP-Discussion] Problem with SCTP_setPrimary()
  • Date: Tue Feb 15 04:52:01 2005
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  • List-id: SCTP Discussions <discussion.sctp.de>

Hi all,
I'm using sctplib-1.0.1, socketapi-1.3.1 and Redhat
9.0 with root priviledge.
I've found a strange problem with SCTP_setPrimary()
Let's say: I have two machines MN and CN as in the
following:

Router A******Router B
* * *
* * *
* * *
MN CN
MN has two interfaces: eth0 to Router A and eth1 to
Router B. CN has one interface eth0 to Router B.

Now, I use my echo_tool (a slightly modified
echo_tool.c with auto changing primary path using
SCTP_setPrimary after 30s) in CN.
I use my dat_sctpserver(a slightly modified
echo_server.c which don't echo data back) in MN.

MN_eth0: 2001:...cbe5
MN_eth1: 2001:...d227
CN_eth0: 2001:...75bb
(IPv6 addresses are used. Use MN_eth0, MN_eth1 for
short)
MN: #./dat_sctpserver -V -s MN_eth0 -s MN_eth1
CN: #./echo_tool -d MN_eth0 -d MN_eth1 -l 1380 -n
60000 -r 7777 -V

As a result:
1) From 0th sec to ~20th sec, CN sent data to MN using
through MN_eth1. Perfectly fine.
2) From ~20 to ...~48.948683, SCTP_setPrimary() was
executed. CN sent data to MN through MN_eth0 and
MN_eth1.
=> WHY? SCTP should send data through primary path
only, right?

3) From ~49, a "Network change...MN_eth0 is
UNREACHABLE" was appeared in CN's console. Then CN
sent data through MN_eth1 !
=> WHY? I did not unplug/down any interfaces. All
pings to all of the interfaces were OK.

The expected behaviors are: In 2)and 3), CN should
send data through MN_eth0 and MN_eth1 only in a short
period. Then CN should send data to MN through MN_eth0
only.

BTW, I attach my dat_sctpserver.c and my echo_tool.c
for your reference at
http://www.comp.nus.edu.sg/~levinhda/matlab/dat_sctpserver.c
and
http://www.comp.nus.edu.sg/~levinhda/matlab/echo_tool.c
.
I aslo attach my ethereal dump at
http://www.comp.nus.edu.sg/~levinhda/matlab/sctpdump_7_dat_echo_tool
for your reference.
Thank you very much.
Sincerely yours,
Le Vinh Dat




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