3Com PLM Series, NCG-PLM manual Avoiding Single Point of Failure SPF Issues, SPF Overview

4 Avoiding Single Point of Failure (SPF) Issues

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)

4.2Automatic 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

6PLM Series Network Configuration Guide