asterisk users - Jul 2009 - 1.6.0.10: server locks up on iax max_retries

I've * in a small office with 10 internal sip extensions on aastra's.
Outgoing is pstn over dahdi, voip over teliax and iax to another office.

This morning no calls could be made: iax to branch offfices, voip iax
over teliax, pstn, or even internal extensions. The aastra's showed
"Not
in Service". A "core restart now" got everything working again.

Before I restarted, CLI was getting these messages:

[Jun 18 10:23:56] WARNING[763]: chan_iax2.c:2434 __attempt_transmit: Max
retries exceeded to host 8.14.120.23 on IAX2/8.14.120.23:4569-14100
(type = 6, subclass = 11, ts=861156, seqno=80)
[Jun 18 10:23:56] WARNING[762]: chan_iax2.c:2434 __attempt_transmit: Max
retries exceeded to host 8.14.120.23 on IAX2/8.14.120.23:4569-14100
(type = 6, subclass = 2, ts=861390, seqno=81)
[Jun 18 10:24:06] WARNING[761]: chan_iax2.c:2434 __attempt_transmit: Max
retries exceeded to host 8.14.120.23 on IAX2/8.14.120.23:4569-14100
(type = 6, subclass = 11, ts=871171, seqno=82)
[Jun 18 10:24:16] WARNING[764]: chan_iax2.c:2434 __attempt_transmit: Max
retries exceeded to host 8.14.120.23 on IAX2/8.14.120.23:4569-14100
(type = 6, subclass = 11, ts=881187, seqno=83)

which I seems to be telling me that channel iax can't reach the Teliax
host. Why is it continuing to retry? Isn't max_retries 4? Here it seems
to trying 83 times - isn't that what seqno means? There have been no
such messages since the restart.

But my real concern is why didn't pstn or iax calls direct to the other
office or internal extensions work? It was lucky I was available to
remotely restart asterisk. Was all this because of the Max_retries
warning? Or is that warning the result of an underlying fault? And if it
happens again, how can I find out what's causing the problem?

sean


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