VBrick Systems VB6000 Network Considerations, Assigning Multicast Addresses, Video Resolution

Table 4. Video Resolution

Video Resolution	NTSC	PAL
Full D1	720 x 480	720 x 576
2/3 D1	480 x 480	480 x 576
1/2 D1	352 x 480	352 x 576
SIF	352 x 240	352 x 288

Network Considerations

A number of features that address video stream handling across networks are described below. These include:

Assigning Multicast Addresses

IP Address Configuration using Host Names

IP Differentiated Services (Diffserv)

VBrick Video Stream Handling

Network Jitter

Assigning Multicast Addresses

Many factors must be considered when designing a multicast address infrastructure since Ethernet switch implementations can significantly vary between vendors. Furthermore, multicast addressing techniques rely on an Ethernet to IP Address mapping rule, which does not guarantee a unique physical address. In fact, it is possible to create multicast addresses that differ from an IP perspective, but overlap when presented to the Ethernet network. Addresses created in this situation can cause significant network and operational problems.

Specifically, multiple IP Addresses are mapped into the same physical layer address. For example, all IP multicast addresses with the same or differing first octet, and the second octet differing by exactly 128, map to the same physical address (226.5.5.4, 227.5.5.4, and 228.133.5.4 all map to the same physical address).

Another factor to keep in mind when assigning multicast addresses is that 224.x.x.x is a range containing reserved addresses, particularly in the range 224.0.0.x. For example, 224.0.0.1 is the 'all hosts' multicast address and 224.0.0.2 is the 'all routers' reserved address. Other 224.0.0.X numbers are reserved for RIP, OSPF, DVMRP, etc. Here are some recommended rules for multicast IP Address assignment:

1.Do not use 224 in the first octet since many of these are reserved.

2.Use a digit between (225–239) for the first octet and standardize on it for each network.

3.In the second octet, either use numbers from 1–127, or 129–255, do not mix ranges on a given network.

IP Address Configuration using Host Names

This feature provides VBricks the ability to unicast to one another, recognizing each other by Host Name instead of IP address. This is especially useful when appliances are running DHCP, since IP addresses can change between being rebooted, whereas Host Names remain the same unless manually changed by the user. Each IP address that can be configured using

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