3Com NCG-PLM - Manual (Page 6)

6 PLM Series Network Configuration Guide
4.1 SPF Overview
Critical network configurations (such as those trans-
porting audio signals) should avoid “Single Point
of Failure” (SPF) scenarios to the greatest extent
possible. SPF failures can occur when a network has
been designed in such a way that failure of a single
part of the network can cause the entire network to
fail or cease operation. A network that has not been
designed with the appropriate fail-safe measures
to avoid SPF issues can suffer a breakdown in the
transport of audio and control data, resulting in the
worst case scenario for any professional sound
engineer: dead silence.
The use of redundant network and audio cabling
and switches, as well as the careful selection of the
proper network topology for your application, are
effective tools in avoiding SPF issues.
The PLM Series has been designed with special
features to help prevent this type of system-wide
network breakdown. These include:
Auto input priority switching (managing multiple •
signal sources)
Support for redundant device sources (e.g. the •
same device providing both analog and AES
sources simultaneously to the network)
Support for redundant network paths (via redun- •
dant rear panel Ethernet ports on the PLM)
4.2 automatic Priority Input
Switching
The user-selectable automatic input priority switching
feature in the DLC PLM Edition software is located
on the I/O Config tab of the Input Configuration page
(see figure 4.1). Four levels of input priority are of-
fered, each of which can consist of Analog, AES 1,
AES 2, and Dante. In the event of a loss of signal to
the first priority input, the system will instantly switch
to the next designated priority input and restore audio
connectivity to the system.
Full information on how to select user input priorities
is contained in section 9.12.3.1 of the PLM Series
Operation Manual.
Figure 4.1: Priority input settings are located in the Input Configuration page
4 avOIDINg SINgLe POINT OF FaILURe (SPF) ISSUeS