3Com NCG-PLM, PLM Series manual PLM / Dante Network Size Limitations, Stage Right

Network Connections and Topologies 5

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Figure 5.2.6: Combined network topology

distances. The recommended LinkSys switch can be upgraded with SFP modules to support fiber connec- tions (See section 7, References and Definitions, for more information on SFP.)

5.4PLM / Dante Network Size Limitations

The information below is provided to give an overview of the terminology and concepts that are used when describing a PLM network and its functions. Further explanations of terminology used can be found in section 7, References and Definitions.

			Link speed [Mbps]
		System type	1*	2**
		Source	100	100
		Backbone	100	1000
		Sink	100	100
			Network diameter
			[# of “hops”]
			14	62
Latency setting 1	0.8	ms	1	4
			1	1
			2	9
Latency setting 1	1.3	ms	4	19
			14	>20
			56	256
Latency setting 2	4.0	ms	9	45
			7	34

*PLM/DLP without external switches or with 100 Mbps switches (not a recommended setup!)

**Recommended PLM only example with Gigabit switch backbone

Table 5.4: PLM network diameter guide

A cable connection from one network port to another is often referred to as a hop.

The maximum size of a network is often referred to as the network diameter. The optimal network diameter is defined by the time it takes for a packet to get from one device to another across the furthest point in the network, in terms of communication time.

Most of the time consumed in the path, generally referred to as latency, is the hardware reaction and transmission time. The time consumed for the packets to travel over the network Ethernet cables themselves is very small in comparison. If we assume 100 m copper cables for all hops, we can present some simple rules for how many hops are permitted from any Dante source device to any of its recieving

PLM Series Network Configuration Guide 11