is a major factor in the CPU load on participating AVB switches, and a high number of AVB endpoints may influence
the maximum number of streams supported.
• Always use P1 of the TC-5 to connect to P2-5 of the TesiraFORTÉ X.
• If a 3rd party switch is connected to P2-5 of the TesiraFORTÉ X it must be a non-PoE capable switch. Damage to
the TesiraFORTÉ X will occur if PoE is injected to P2-5 from an external source. (A PoE port that has been disabled
can still cause an issue at the hardware level.)
AVB Network Diameter
A network hop is a link between two networked devices.
Biamp recommends a maximum AVB network diameter of 9 hops in order to guarantee that 2ms deterministic latency is
maintained.
AVB networks that consist of purely gigabit-capable devices may allow the maximum network diameter to be 9 or more
hops while maintaining 2ms deterministic latency. The total latency will be dependent on numerous variables
including switch models being used and the firmware they are running, network size and topology, and the total number
of AVB streams and AVB devices on the network.
Every network device has a pass-through latency, including AVB talker and listener endpoints and copper or fiber links
and converters. The sum of all latencies must be less than 2ms to guarantee the ability to maintain
playout synchronization across all endpoints at 2ms (2,000µs). The path from talker to listener must be under 2ms for
all talker-listener paths in the system.
Biamp AVB endpoints incur 125µs latency per source and sink device.
Pass-through latency on switch hardware varies from 125µs to 200µs per device. Because the exact latency is
unknown, we assume the worst-case scenario of 200µs across all network hops. Eight network switches at 200µs each,
plus two endpoints at 125µs each totals 1850µs, leaving 150µs to spare. A daisy-chained system with 10 network
devices requires 9 connecting links or "hops." This is how we determine the 9-hop maximum diameter.
A network comprised only of devices with a 125µs pass-through latency would allow a theoretical maximum of 15 hops
while respecting the 2ms cumulative latency.
In practice, most networks end up with a blend of network device latencies. Some hardware has 125µs pass-through,
while other devices may be 150µs pass-through, and others may be 200µs pass-through. Fiber converters may add
considerable latency to a hop. This should be taken into account when designing the network and may allow for
flexibility in the hop limit that is chosen.
https://support.biamp.com/Tesira/Miscellaneous/TesiraFORTE_X
Updated: Thu, 01 Dec 2022 17:48:44 GMT
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