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Re: [hylafax-users] T.30 T2 timeout, expected signal not received



On 2004.08.11 10:02 Stephen Carville wrote:
This looks like the Last Known Problem -- suggestions on fixing it are

wqelcome :-)  In the last seven days this has accounted for 29 errors
in 1289
pages.

Aug 11 07:24:15.49: [25776]: RECV received RCP frame
Aug 11 07:24:17.08: [25776]: --> [10:NO CARRIER]
Aug 11 07:24:17.08: [25776]: MODEM set XON/XOFF/DRAIN: input ignored,
output
 disabled Aug 11 07:24:17.08: [25776]: MODEM input buffering disabled
Aug 11 07:24:17.08: [25776]: <-- [9:AT+FRH=3\r]
Aug 11 07:24:20.95: [25776]: --> [7:CONNECT]
Aug 11 07:24:21.21: [25776]: --> HDLC<6:FF C8 FD F4 40 00>
Aug 11 07:24:21.21: [25776]: --> [5:ERROR]
Aug 11 07:24:21.21: [25776]: MODEM Command error
Aug 11 07:24:21.21: [25776]: FCS error

That "FF C8 FD F4 40 00" is the PPS-EOP signal, but it's missing one byte at the end, so it is a corrupt HDLC frame and produces an FCS error (thus, the ERROR message). We expect the sender to retransmit the signal. So we try again...


Aug 11 07:24:21.21: [25776]: <-- [9:AT+FRH=3\r]
Aug 11 07:24:21.26: [25776]: --> [7:CONNECT]
Aug 11 07:24:22.24: [25776]: --> [20:0F 00 00 00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00 00]

And behold what is this???


Aug 11 07:24:22.24: [25776]: --> [20:00 00 00 00 00 00
 00 00 00 00 00 00 00 00 00 00 00 00 00 00]

Well, either the sender is actually sending a bunch of zeros, or something is wrong with the receiving modem. I guess that a PBX in-between DCEs could also cause this problem, or perhaps a really nasty telco problem.


My guess is that whatever happened to the signal happened to it during the PPS-EOP HDLC frame and caused it to lose one byte. That error persisted through the rest of the session, causing the zeros, etc.

At this point, check your lines, check your connection, check your modem. If all else fails try a different modem (make and model) and see if the error continues.

Lee.

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