[SR-Users] problems with use_dst_blacklist and ICMP "Destination Unreachable"

[Valentin Christoph]

Hi all,

Question:

  *   Does the TM destination blacklist work, if destination host responds with ICMP "Destination Unreachable"?

Discussion:

I have got an IMS scenario, where I think the destination blacklist is not working and try to find the reason.

I use UDP between two Kamailio SIP Proxies (P-CSCF and S-CSCF) and send a SIP request to the primary instance of the S-CSCF.

However the destination Kamailio has been stopped with kamctl stop before and so the destination machine responds with ICMP "Destination Unreachable". DNS Failover towards secondary S-CSCF instance works perfectly.

Destination Blacklist does not work. I.e. the next SIP Request is sent to the primary host again, before failover to secondary host applies. I would have expected the request would be sent to secondary host immediately.

>From the description in doc/dst_blacklist.txt
[...] A destination is added to the blacklist when an attempt to send to it fails (e.g.
timeout while trying to send or connect on TCP), or when a SIP timeout occurs
while trying to forward statefully an INVITE (using tm) and the remote side
doesn't send back any response.[...]

I think the destination blacklist does not work, because an ICMP Response "Destination Unreachable" is received.

Second question:

  *   How could I avoid the problem?

Thanks, Christoph



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