The problem occurs when the software is expecting the packet in a certain timeframe so that it can reassemble it in a timely manner. It's not a big deal with a web page or something along that lines. But when a voice application cannot get reassembled in a timely manner, you'll surely notice it!
-----Original Message----- From: Joel Maslak To: [EMAIL PROTECTED] Sent: 12/23/2003 10:41 AM Subject: Re: [Asterisk-Users] Asterisk SIP Packet Time (20ms) On Tue, 23 Dec 2003, Rich Adamson wrote: > If a collision or dropped packet occurs (in a voip udp environment) there > is no way to retransmit the missing/damaged packet. Missing one packet isn't > a big deal, but if you have collisions and/or dropped packets, there is a > very high probability that lots of packets will be dropped. If too many > are dropped, you'll hear the result in the undecoded voice as choppy > voice. Actually, collisions occur at Layer 2, not Layer 3, and the layer 2 hardware automatically resends packets involved in a collision - layer 3 is never aware of it happening (although it may cause additional delay). Eventually the ethernet card will give up if too many collisions occur during retries, but this is very rare in practice unless the network is *VERY* loaded. > Assuming alaw/ulaw codecs in use (about 80k bps), a half duplex 10 meg > ethernet would handle roughly 20-25 rtp sessions before bumping into the > problem (your milage may vary). The majority of the folks on this list > seem to be running home/soho systems and would likely never run into the > issue. But the heavier users will. For a duplex mismatch, my experience is that if one end on a 100 Mb/sec link is half and the other is full, bandwidth is limited to about 8 Mb/sec max. This is based on some tests I've accidentally conducted. If you try to send 9 Mb/sec over that link, yes, some packets will get dropped as they simply won't fit. (But I do agree that for a half-half link, you can get about 20 Mb/sec) -- Joel _______________________________________________ Asterisk-Users mailing list [EMAIL PROTECTED] http://lists.digium.com/mailman/listinfo/asterisk-users _______________________________________________ Asterisk-Users mailing list [EMAIL PROTECTED] http://lists.digium.com/mailman/listinfo/asterisk-users