> I am using asterisk-1.6 with chan_ss7-1.3 on sangoma cards (a104de.) > Everything is working fine but I notice many time the following > message on the logs: > > NOTICE[22852] l4isup.c: Write buffer full on CIC=12 (wrote only 160 > of 240), audio lost (suppress 1). > NOTICE[21785] l4isup.c: Write buffer full on CIC=12 (wrote only 0 of > 240), audio lost (suppress 133). > > Anybody knows what can cause this ? > I think that this impact very badly the sound quality (I have many > customer complaints...) i'm updated FAQ on http://www.voip-info.org/wiki/view/Asterisk+ss7+faq from some old source try activate jitter buffer http://www.voip-info.org/wiki/view/Asterisk+ss7+configuration [jitter] jbenable = yes jbmaxsize = 1000 jbresyncthreshold = 1000 jbimpl = adaptive --snip-- Write buffer full on CIC=4 (wrote only 0 of 160), audio lost. Sep 19 18:41:08 NOTICE10930 l4isup.c: Write buffer full on CIC=4 (wrote only 0 of 160), audio lost. Sep 19 18:41:08 NOTICE10930 l4isup.c: Write buffer full on CIC=4 (wrote only 0 of 160), audio lost. Sep 19 18:41:08 NOTICE10930 l4isup.c: Write buffer full on CIC=4 (wrote only 0 of 160), audio lost. Actually, the "Write buffer" is a kind of jitter-buffer. It is inside the zaptel driver and is initialized by chan_ss7 to 4 * 160 bytes (80ms). You can increase it to some other multiple of 160, but it requires a recompile, and will also increase the audio-delay. The "write-buffer full" problem often occur because of jitter on the IP-net. In IP-networks, there is allways a time-delay from the time a packet is sent to it get received at another host. This delay is unfortunately not allways the same. Sometimes, the packets will arrive too slow, and sometimes they will arrive too fast. When they arrive too fast, the send-buffer is filled, chan_ss7 writes the "Write buffer full" and then drop the packets. This problem does not occur in the conventional circuit-switched telephone network, since it is completely synchronous and a dedicated (logical) circuit is reserved between the sender and receiver. To get around this problem, you can setup trafic-shaping on the network, insert a bigger buffer in chan_ss7 (which will cause more delay), to even-out the difference in time-delay. Maybe it will helpl to configure the routers to "chop up" big packets in order to get the small RTP packets going smoothly. --------------------------------------- Marek Cervenka =======================================
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