ClearOne Digital Media - Manual (Page 13)

pg 13 StreamNet Digital Media and System Design Reference Guide
Common AV Signals and Interfaces
Although delay through a network may on the average be very low, there is little effort made
to limit that delay in a traditional IT network. Since there is no concept of “time” in an IT
network, there is nothing in the network infrastructure itself that can aid in synchronization.
Additionally, the network itself does not prevent network congestion, so data can be lost if
buffers are inadequate or link bandwidth insufficient for the offered traffic.
IT networks count on higher level protocols to handle congestion such as TCP which works
by throttling transmission and retransmitting dropped packets. This is adequate when long
delays are acceptable, but will not work where low deterministic delays are required.
The typical way these last two problems are handled today is with buffering, but excessive
buffering can cause delays that are annoying in the consumer environment and completely
unacceptable in a professional application.
One way to allow existing IT-oriented networks to be used for A/V streams is to “manage” the
network at a higher layer or to impose strictly defined, inflexible configurations. For example,
in the professional market, there are a few systems in place that can provide adequate
delays and guaranteed bandwidth, but they require a single proprietary solution, and need
to be reconfigured every time a new device is added. CobraNet is an example of this kind of
architecture.