[SCTP] ICMP unreachable message reenables data transmit

[Michael Tüxen]

On Apr 30, 2011, at 12:15 PM, Schoch Christian wrote:
> 
> Zitat von Michael Tüxen <Michael.Tuexen at lurchi.franken.de>:
> 
>> On Apr 30, 2011, at 9:11 AM, Schoch Christian wrote:
>> 
>>> During a measurement with CMT-SCTP and PF i figured out, that sometimes a ICMP Destination unreachable message triggers a message transmission on an inactive data path that has been primary before.
>>> 
>>> It looks as the ICMP message is reseting the inactive state back to active without reseting RTO.
>>> 
>>> This behavior is triggered by a returning heartbeat message when no ICMP unreachable by data is sent quite before.
>>> 
>>> Test system are two multi-homed hosts with FreeBSD8.1 and a WANem host between.
>>> 
>>> A wireshark log can be provided on demand (quite large).
>> Hi Christian,
>> 
>> any chance to upgrade the FreeBSD machines to head or to use newer
>> SCTP sources, which I could provide? It would require a recompilation
>> of the kernel...
> 
> It is possible, but the results could be provided not until next week
> if a reboot is necessary.
> I can use any sources you could provide me since nothing else is done at this systems.
OK, but maybe I can try to understand what is going on.

How many paths do you have? One is inactive, but was primary, so it
is confirmed. On another one, you get an ICMP (which one? Port unreachable,
host unreachable, ...). Do you have more than two paths?

The ICMP message would not reset the RTO, since you need an ACKed TSN
or a HB-ACK to to that. Since it is inactive, it is missing these.

Sending on an inactive path is OK, as soon as you enter the dormant
state, which means all your paths are inactive.

Are you using the PF support for CMT?

Best regards
Michael
> 
>> 
>> Are you using IPv4 or IPv6?
>> 
> 
> IPv4
> 
> 
>> Best regards
>> Michael
>>> 
>>> Regards,
>>> Schoch Christian
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>> 
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> 
>