Biamp A4 - Manual (Page 185)

System Design
System Network Considerations
The computer must have a 10/100 BaseT network card (NIC) installed. When connecting directly
to the Ethernet port on a single Audia®
unit, a 'cross-over' CAT5 cable is used. When connecting
to a network (or system) of multiple Audia units, a 'straight-through' CAT5 cable is used (via an
Ethernet switch). A separate switched Ethernet network is strongly recommended for CobraNet®,
and is mandatory when using multicast bundles. Ethernet switches (not 'hubs') must be 10/100
BaseT compatible, with sufficient ports for connection to each Audia
unit (multiple switches may
be used). If Ethernet switches are 'managed', be careful to assign all CobraNet connections to
100 BaseT, and all Ethernet connections to 10 BaseT. These connections also use 'straight-
through' CAT5 cables. When a system using only two Audia devices has been configured, and
the computer connection is removed, both Ethernet and CobraNet connections may be made
directly between the two units using 'cross-over' CAT5 cables.
Ethernet and CobraNet both have a cable length limitation of 100 meters, between the Ethernet
switch and an Audia device. However, fiber-optic cable may be used to extend this distance
limitation to 2 km. Fiber-optic cable can be used with switches that have fiber-optic ports, or
media converters can be used to interface fiber-optic cable with standard RJ-45 ports.
Due to network delay, CobraNet has a limitation of 7 'hops' (one-way transmissions) within a
network. Typically, CobraNet transmits 32 channels of digital audio on 4 'bundles' of 8
channels. Under these circumstances, each CobraNet device would be able to transmit digital
audio to no more than 4 other CobraNet devices, and receive digital audio from no more than 4
other CobraNet devices, within a network. Also, a CobraNet Latency setting of 1.33mS (see
Equipment Table ) would then reduce the total number of CobraNet bundles (transmit + receive)
for a CobraNet device to four. However, "flexible CobraNet bundles" (see below) offer some
exceptions to these CobraNet restrictions.
Audia software utilizes the concept of "flexible CobraNet bundles". Flexible bundles can comprise
any number of channels in the range of one to eight. Their size is adjusted automatically by the
compiler on a case by case basis according to the number of channels passed between different
Audia devices in the system. Accordingly, the total number of bundles that can be used in any
Audia device is larger, up to sixteen, but depends upon the number of channels being transferred.
The table below gives some guidelines about the communication bandwidth of an Audia device
when using flexible bundles. Columns Rx and Tx indicate the absolute maximal number of
channels that can be received or transmitted. Column Rx / Tx gives the maximum number of
channels that can be received and transmitted at the same time. Flexible bundles are used only
in
Extended compilation mode.
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