network audit form

The videoconferencing rate is the sampling rate of the network audit form, not the actual bandwidth that the video call requires. In other words, the data payload of videoconferencing packets is filled with 384 kbps of voice plus video samples. IP, UDP, and RTP headers (40 bytes per packet, uncompressed) need to be included in IP/VC bandwidth provisioning, as does the Layer 2 overhead of the media in use. Because (unlike VoIP) IP/VC packet sizes and rates vary, the header overhead percentage also varies, so an absolute value of overhead cannot be calculated accurately for all streams. However, testing has shown that a conservative rule of thumb for IP/VC bandwidth provisioning is to assign an LLQ bandwidth equivalent to the IP/VC rate plus 20 percent. For example, a 384-kbps IP/VC stream adequately is provisioned with an LLQ of 460 kbps

The Cisco LLQ algorithm has been implemented to include a default burst parameter equivalent to 200 ms of traffic. Testing has shown that this burst parameter does not require additional tuning for a single IP videoconferencing (IP/VC) stream. For multiple streams, this network audit form parameter can be increased as required