Telex IP-223 technical manual Network Requirements, Bandwidth, Multicast

CHAPTER 2

Communications System Design

Designing an IP-223 system requires an understanding of the radio network and how the various radios and communication equipment are connected.

The first step in designing an IP-223 system is to create a roadmap of the radio, console, and any other communication equipment locations. This roadmap must include the following:

•Multicast addresses for each channel of TX (transmit) and RX (receive) communication.

•Port numbers for each channel of TX and RX communication.

•Base IP Addresses assigned to each console and IP-223 on the network.

Network Requirements

Bandwidth

Each VoIP channel requires 50kBit of bandwidth while active. Full-duplexconversation (audio in each direction) requires 100kBit of bandwidth.

NOTE: Most radio voice communications are half-duplex(only in one direction at any one time), thus requiring 50kbits.

Some radio systems transmit go-aheadbeeps when it is clear to talk. In order for the console operator to hear the beeps, the system must support full-duplex communication. Full-duplex bandwidth may only be required for the first few seconds of a conversation, due to the brief nature of the go-aheadbeeps at the beginning of the transmission.

When using a PIB, TDI, C-6200, or the NI-223 for a telephone connection, 100kBit is required since it is a constant, full- duplex conversation.

Multicast

In general, Telex systems require multicast to function. The network must be able to support the multicast traffic generated by the system.

It is very common for networks to enable multicast after an IGMP (Internet Group Management Protocol) join message is sent out, and then prune off branches after a period of time. Due to the intermittent usage patterns of two-way radios, such a system can appear to work flawlessly for a period of time, then no longer work.

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