Rule of Thumb for VoIP: 1) If the link speed is T1 or better use G.711 codec which uses 64kb per call (also refer to as a voice flow). If the link speed is less than T1 use G .729 which use 8kb per call or similar codec with built in compression.
2) QoS. VoIP is successful when the delay is small and constant (Jitter). G.114 defines an acceptable one way end to end delay of 0 - 150ms. Delays as high as 400ms might be tolerated if both parties are aware of the problem. There are many factors involved in a delay budget: Processing, Serialization, and Propagation. This refers to the time it takes to digitize the voice waveform , put into a packet and transfer the packet to an interface and send the packet across the network where the packet is converted back into an close copy of the original analog waveform. As you can see VoIP dictates small packets with a little delay as possible and that the packets arrive in a steady, constant flow. Which brings up Jitter. Jitter is when the delay is not constant. The conversation becomes choppy because the voice packets arrive at a different spacing than they were spoken by the sender. Voice packets are best effort and never retransmit a packet. 3) Packet size. Data likes large packets, is more tolerant of delays and jitter, but all packets must be received. Dropping packets leads to data corruption, so retransmitting packets are allowed. To minimized delay and reduce Jitter, change the MTU to allow voice to flow and not get stuck behind large data packets. David L. Blair ""dj"" wrote in message news:[EMAIL PROTECTED] > After reviewing configs on CCO regarding running VoIP over a dedicated > pt-pt T1 (with encap ppp), do I really need to run multi-link ppp > template if I don't need to do link fragmentation & interleaving on > serial interface? All 24 channels are available for data > > I don't see any serialization issues, thus no need to fragment large > packets - thus no multilink interface config required. Am I thinking > this thru correctly, or is there something that am I missing here? > > regards, > dimitri Message Posted at: http://www.groupstudy.com/form/read.php?f=7&i=65388&t=65370 -------------------------------------------------- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
