Void Bias V3 User Manual - page 31
10 Network operations
Network capabilities and network setting menus are avail-
able only for Bias Series amplifiers equipped with a AESOP
board.
AESOP stands for AES3 and Ethernet Simple Open
Protocol. Void’s AESOP is designed to provide high reliability
to live applications in harsh environments where Quality of
Service must be guaranteed. Electromagnetic and radio
frequency interference (EMI and RFI) originating from a high
power audio and light system must not degrade audio qual-
ity or cause a control link interruption. Moreover, a single
cable or device failure should not affect the overall system
performance.
10.1 Introduction to AESOP
The AESOP standard can transport a single bidirectional
Ethernet 100 Mbps control data stream and two separate
AES3 digital audio monodirectional streams using one Cat5
cable.
All Bias Series amplifier with the optional AESOP board
installed are equipped with at least two RJ45 connectors,
each of them being a single AESOP port, capable of sending
and/or receiving data and audio.
If the amplifier has only two RJ45 plugs, these will be on
the front panel. If four plugs are present, the rear two will
be “primary” ports, while the two on the front panel are
“secondary” ports.
Primary ports allow both data and AES3 streams; second-
ary ports, on the other hand, are data-only ports, allowing
Ethernet connections only.
Cat5 standard twisted pair cables shall be used for connec-
tions up to 100 meters (328 ft). RJ45 pinout must comply
to TIA/EIA-568-B and adopt the T568B scheme pinout, as
show in TABLE 1 p. 23.
Please note that even if crossed Ethernet cables
would work control wise, crossed cables are not
to be used for AESOP connections: they will not
allow the AES3 streams to flow correctly.
10.1.1 Data stream
The data stream in the AESOP is implemented by a 100 Mbit
Ethernet connectivity with auto-sense.
Each device can use a static IP address assigned by the
user. Alternatively, it can be set to automatically configure
itself without user intervention following the Zeroconf
protocol.
The dual port design in Bias Series amplifiers allows for
daisy chain and redundant ring topologies. A fault-bypass
built-in feature takes into account the possibility of loosing
an intermediate device or having a faulty cable link without
compromising the ring integrity.
The AESOP board detects bad quality connections by
counting errors on the Ethernet control. Faulty connections
are automatically switched from 100 Mbit/s to 10 Mbit/s
to attempt to keep the link active even in the worst case
scenarios.
10.1.2 Audio
Audio is distributed to devices via the AESOP protocol by 2
independent and separate AES3 streams labelled AES3-A
stream, AES3-B stream. These are carried by two Cat5 wire
pairs unused in the 100 Mbit Ethernet protocol.
AES3 is a license free and well known standard guarantee-
ing low-latency, high reliability and excellent audio quality.
A single AES3 stream can carry a stereo audio signal. The
AESOP protocol can therefore handle four audio channels.
When a Bias Series amplifier is powered off or if it is unavail-
able, a passive high frequency relay circuit allows the audio
signal to pass through, preserving the network chain con-
nection integrity.
When the device is powered up, the internal circuits auto-
matically select the most appropriate AES3 stream direc-
tion and bypass the relay, re-buffering actively the AES3
signal. The direction is maintained until errors are detected
on the AES3 receiver circuit. When errors or link failure are
detected, the direction is swapped, to build-up a new path
for the audio. In a fraction of a second (no more than 50ms),
some of the devices in a ring will swap to the other direction,
restoring the audio streaming.
10.1.3 Ethernet internal switch
All control data streams in the AESOP system are transport-
ed via an Ethernet protocol. Inside all Bias Series amplifiers
is an Ethernet switch connected to each RJ45.
This means that the bidirectional data stream can enter/
exit one port and exit/enter any other port, either alongside
AES3 streams or on its own.
Internal routing of Ethernet networking is automatic and not
user controllable. An internal switch provides packet flood-
ing block services in order to allow building networks with a
ring topology.
10.1.4 Forwarding and repeater modes
Each Bias Series amplifier can be configured to handle the
pair of AES3 streams embedded in the AESOP protocol in
one of two basic network modes: repeater and forwarder.
These are true connection “building blocks”; it is therefore
important to understand these two modes thoroughly be-
Bias Series User Guide V1.0
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