Operating Multirack In A 24/7 Environment; Always Connect To - Comrex ACCESS MultiRack Product Manual

OPERATING MULTIRACK IN A 24/7 ENVIRONMENT

XII.
MultiRack can be configured for "always on" operation. This allows for constant STL communication and operations
requiring long-term connections.
In BRIC Normal mode (the default mode of operation), MultiRack transfers all its audio data via the UDP 9000
protocol. This is in contrast to most web-based connections like browsing and email, which use the bidirectional
TCP protocol. UDP, unlike TCP, is not "connection oriented" (i.e., no virtual connection actually exists in this protocol
layer between the devices). In UDP, the transmitter simply launches packets into the network with the correct
address, hoping the network will make its best effort to deliver the packets in a timely fashion. If a packet is delayed
or lost, no error message is sent from the receiving unit and no packets are retransmitted. It is up to the receiver to
cover up any lost data, if possible. This allows the Internet to deliver packets with the smallest amount of overhead
and delay. As there is no coherent connection built between the codecs, there isn't any connection to break in the
event of network failure. The encoder simply propels packets into the network, regardless of whether they arrive. If
the network fails and is later restored, the packets stream will be restored to the decoder.
For most applications like remote broadcasting, it's useful to simulate a connection-oriented stream, so MultiRack
uses a low-bandwidth sub channel to deliver information back to the encoder about overall connection status. It
does this in its "application layer", rather than in the "transport layer" where UDP exists. By default, it monitors the
health of a connection and if no data is detected as received by the decoder for 60 seconds (this is a user defined
timeout), it "tears down" this connection and reverts to an idle state. This indicates to the user that the network
has failed and the problem must be addressed.
The benefit in having the connection protocol in the application layer is that its use is optional. For 24/7 operation,
there's no advantage to the connection ending if no data is received for the timeout interval.

AlwAys connect to

To set MultiRack for 24/7 operation, several parameters are changed:
1 The timeout value is set to infinity; the connection will never be torn down regardless of data
status.
2 MultiRack is configured to re-establish the connection in the event of a power-up.
The local Disconnect control is disabled. The Disconnect function on the receiving side is still
3
enabled, but will result in an immediate reconnection by the initiating side.
As seen in Figure 65, under Connections in the System Settings tab (with "Show Advanced Options" selected),
there is an Always Connect To option with a pull-down menu of your unit's available connections. Selecting "ON" in
these remote connections will configure the unit for 24/7 operation to that remote. (No configuration is necessary
on the remote side.)
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