[asterisk-ss7] Strange interrupt issue with zaptel and chan_ss7

Kai Militzer km at westend.com
Wed Jul 12 03:10:32 MST 2006

Hello everyone,

I solved my problem, so I tought I give you an update.

> Then finaly I came across the behavior that puzzles me. Asterisk was 
> running with two instances over the crosslink and the console screen was 
> blanked on the console. So I wanted to press Shift to unblank it, but 
> accidently pressed the CapsLock key. When the screen was unblanked and I 
>  started to type, I realized, that CapLock was on. I pressed it again 
> and in this moment, I got a CRC16 error. I thought that was strange and 
> pressed it again twice, and there it was again, Packets from the zaptel 
> driver to chan_ss7 got lost. The same behavior happens, when I press 
> ScollLock or NumLock. The Keyboard runs on interrupt 1 and the TE205P on 
> IRQ11, so there shouldn't be any impact when the keyboard uses this 
> interrupt.

I got the card interchanged with a new one from my distributor. With the 
new card, the problem does not exsists. So the reason for the strange 
behavior was a faulty hardware. That's OK, things like that can happen, 
but what I cannot understand is, that the tests shipped with the zaptel 
source did not detect it.

If I understand correctly patlooptest should reveal problems with bad 
cards, but it went through without problems on my faulty card. I think 
the problem is, that the error I had only surfaced, when a channel in 
the span was completely used (i.e. the complete bandwith of 64kbit is 
used by the signaling channel for SS7). I think that patlooptest does 
not use the full bandwith of a channel and therefore does not detect the 
error and it tests only one (the first) channel of a span. As I am not a 
developer and my C knowledge tends to zero, I am not sure, if my claim 
is right. But if it is, zaptel IMHO needs a test, that uses the full 
bandwith of more than one channel to detect faulty cards.

Best regards,

Kai Militzer                 WESTEND GmbH  |  Internet-Business-Provider
Technik                      CISCO Systems Partner - Authorized Reseller
                              Lütticher Straße 10      Tel 0241/701333-14
km at westend.com               D-52064 Aachen              Fax 0241/911879

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