ASTERISK-15141: UDPTL asked to send 77 bytes of IFP when far end only prepared to accept 45 bytes; data loss may occur.

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Summary: ASTERISK-15141: UDPTL asked to send 77 bytes of IFP when far end only prepared to accept 45 bytes; data loss may occur.

Reporter: Alex Oniciuc (alex oniciuc) Labels:

Date Opened: 2009-11-16 03:31:00.000-0600 Date Closed: 2011-06-07 14:07:59

Priority: Minor Regression? No

Status: Closed/Complete Components: Channels/chan_sip/T.38

Versions: Frequency of
Occurrence

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Issues:

Environment: Attachments:

Description: I'm using Asterisk's fax passthrough functionality to send faxes from one t38 enabled Patton to another.

The faxes arrive correctly but the Asterisk logs are full of error messages like:

[Nov 16 09:35:08] WARNING[3762]: udptl.c:1003 ast_udptl_write: UDPTL asked to send 77 bytes of IFP when far end only prepared to accept 45 bytes; data loss may occur.
[Nov 16 09:35:08] ERROR[3762]: udptl.c:292 encode_open_type: Buffer overflow detected (77 + 239 > 244)
[Nov 16 09:35:08] NOTICE[3762]: udptl.c:1014 ast_udptl_write: UDPTL Transmission error to XXX.XXX.XXX.XXX:10008: Message too long

or

[Nov 16 09:35:22] WARNING[3762]: udptl.c:1003 ast_udptl_write: UDPTL asked to send 53 bytes of IFP when far end only prepared to accept 45 bytes; data loss may occur.

****** ADDITIONAL INFORMATION ******

CALL FLOW: ANALOG FAX => PATTON => ASTERISK 1.6.1.9 => PATTON => ISDN

The issue 15586 should have solved the problem but asterisk 1.6.1.9 doesn't implement the patch and the patch isn't portable to the last version: trying to patch 1.6.1.9 in --dry-run returned "8 out of 23 hunks FAILED".

The error correction method is redundancy and is enabled on all three parties.

ASTERISK: t38pt_udptl=yes,redundancy
PATTON A/B: T.38 Redundancy
[Low Speed 3 additional packets]
[High Speed 3 additional packets]

Comments: By: Joshua C. Colp (jcolp) 2009-11-16 08:56:42.000-0600

Unfortunately the fix is not yet in any released version so you can either use a release candidate or wait until the final version is released. Once that is done you will be able to override the maximum datagram size using maxdatagram and make the messages go away.