Biamp Audia Classic Firmware Upgrade Procedure - Manual (Page 11)

Page 11 Biamp Systems | AVB Resource Guide
Q: Can I use AVB with a mixed network?
A: Yes.
Q: What is the latency of AVB?
A: The latency for AVB is very low. Stream Reservation Protocol (SRP) and the
IEEE 802.1Qav Protocol together ensure end-to-end timely delivery of all
reserved media streams. Without these protocols, there is no way to know how
much intervening non-media traffic, or how many media packets, the switches
may queue up.
2ms Maximum
AVB Latency
Processor Processor A/D Converter A/D Converter AVB
Interface
AVB
Interface
AVB
Switch
AVB
Switch
With AVB on a wired Ethernet network, the worst-case travel time is known
throughout the entire network. As a result, only a small amount of buffering is
required and very low latencies – 2ms over 7 switch hops in a 100Mbit Ethernet
network – can be achieved, and even better at gigabit speeds.
Q: What are the network diameter limitations?
A: This is variable and dependent upon forwarding delay of the switches used.
The network must support a round-trip delay within the AVB latency setting. As
Tesira uses Class A latency, this is either 1 or 2ms.
For example, if a switch has a forwarding delay of 150 microseconds (150 μ s),
nine switches will take 1.350ms to move an AVB data stream. Once you then
factor in the endpoint processing delay, you are at the 2ms network limit. This
sample switch would support 10 switch hops. The use of “faster” switches or
uplinks will increase the network diameter. So moving to a 10 Gigabit uplink,
or using a switch with a quicker throughput, will mean more switch hops are
supported.
Q: How will my bandwidth be utilized?
A: The IEEE 802.1Qat Stream Reservation Protocol (SRP) provides mechanisms
for reserving stream bandwidth that allows endpoint applications to configure
the routes, eliminating the need for this type of infrastructure network
engineering. SRP checks end-to-end bandwidth availability before an AV stream
starts. If bandwidth is available, it is “locked down” along the entire path until
explicitly released. SRP works hand-in-hand with the IEEE 802.1Qav Queuing
and Forwarding Protocol.
Qav schedules time-sensitive AV streaming data, ensuring timeliness through
the network. Regular non-streaming traffic is treated in such a way that it
cannot interfere with reserved AVB traffic. Utilizing the AVB protocols, intelligent
devices communicate with the network to provide reliable AV streaming without
the need for the integrator to perform extensive hand-tuning of the network.