[asterisk-dev] t.38 passthrough filters redudant packages ?

[Kevin P. Fleming]

On 09/10/2010 08:24 AM, Kristijan Vrban wrote:
> can it be, that in udptl fax passthrough redudant packages with the
> same Seq No are not transmitted?
> I analyzed a pcap from my carrier to asterisk (1.4) and the pcap from
> asterisk to a linksys spa2102
> And for exapmle the v21-preamble comming from my carrier with the
> seqNr. 00032 is always fourfold, but on the passthrough
> side to the spa2102 has only one v21-preamble with seqnr. 00032. So
> the passthrough filters the redundance ?

Yes. UDPTL frames are not passed through raw (like RTP frames can be in
Packet2Packet bridging mode), instead the UDPTL encapsulation is
removed, missing packets are recovered if possible, and ast_frame
objects are sent to the other side of the bridge, which encapsulates the
content in UDPTL again, adding error correction if configured to do so.

-- 
Kevin P. Fleming
Digium, Inc. | Director of Software Technologies
445 Jan Davis Drive NW - Huntsville, AL 35806 - USA
skype: kpfleming | jabber: kfleming at digium.com
Check us out at www.digium.com & www.asterisk.org