Hi all,

I'm regarding the multihoming function of sctp. I'm using sctplib-1.0.1 and socketapi-1.3.1 in Redhat 9.0.

1)

Let's say:

+ We have 2 connected subnets A and B

+ Mobile node (MN) has 2 interfaces eth0 and eth1. And initially, MN's eth0 and eth1 were in A.

+ MN was sending data to CN which is in B.

Now, if MN's eth1 is unplugged out of A and plugged into B, then the connection is still able to continue sending and receiving data or it will be terminated?

 

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2)

I think it should continue sending data. However, it may not in my case:

Subnet A: a0e

Subnet B: a0f

MN: eth0 is d037, eth1 is d2b2

 

MN:> ./echo_server -V -s ...a0e:..:d037  -s ...a0e:...:d2b2 

(I use ... for short for us to make it clearer)

 

CN>./echo_tool -a -d ...a0e:...:d037 -d ...a0e:...:d2b2 -l 1400 -n 500000 -r 7 -V

 

Now I unplug MN's eth1, the connection hangs for a while (if eth1 is primary) and continue sending data. Then, I plug eth1 into a0f subnet, the connection hangs a while and the "connection losts" announcement appears.

 

Some observations:

MN was trying to send SACK to CN using eth1 with new IP a0f:...:d2b2 (eth1 is now in subnet B).

However, CN was trying to send ABORT to MN's eth1 (through new IP a0f:...:d2b2)

Then, HEARTBEATs, ABORTs and 3 consecutive HEARTBEAT were sent by MN's  eth1 (a0f:...:d2b2) to CN.

Finally, connection losts.

 

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Can anyone enlighten me why the connection is lost?

Any idea is appreciated.

Thank you very much for your helping.

 

Sincerely yours,

Le Vinh Dat