Avaya 555-245-600 manual Design inputs

Design inputs

A Communication Manager system can operate as an independent entity, or can be networked together with other Communication Manager systems. For networked systems, the various Communication Manager systems in the network are generally interconnected by IP tie trunks. If the two members of a given pair of Communication Manager systems in a network are not directly interconnected by tie trunks, calls between the two systems must be tandemed through other Communication Manager systems in the network.

When there is a need to accommodate endpoints in various geographic locations, the customer has the choice to either set up a single Communication Manager system with a site at each location, or use a network of multiple Communication Manager systems to span the locations. The choice of which one is more appropriate pertains to the issue of scalability. An extremely large number of endpoints might mandate the use of multiple systems.

While Communication Manager systems have been designed with an IP infrastructure, they also support circuit-switched endpoints, and the full complement of traditional DEFINITY features. However, customers usually realize a significant advantage when those customers implement an IP-oriented solution for systems that are geographically dispersed.

Each endpoint and Media Gateway is assigned to a Network Region when its IP address is administered. Also, each Network Region is administered with a codec preference list, which is a list of up to five codecs that are supported by that Network Region. Uncompressed G.711 and compressed G.729 are the most commonly used codecs in Communication Manager systems. Each Communication Manager system is administered with the Internetwork Region Connection Management (IRCM) matrix, which provides enough information to specify which codecs to use when completing a call between Network Regions.

Conversely, if the IRCM does not specify a codec set between two Network Regions, calls cannot be completed between those regions over an IP connection. For instance, the manager of an office building can use a single Communication Manager system to service all the individual lessees, with a separate Network Region for each company. Those Network Regions generally would not be connected by the IRCM because independent companies would be unwilling to share each others’ resources. Subsequent sections of this chapter further explain sharing resources across connected Network Regions.

Multiple Communication Manager systems are often networked together by IP tie trunks, although circuit-switched tie trunks can also be used. If the two members of a given pair of Communication Manager systems in a network are not directly interconnected by tie trunks, calls between the two systems must be routed through other Communication Manager systems in the network, or through the public switched telephone network (PSTN).

Although Avaya products are IP enabled, the products must interface with circuit-switched endpoints and systems. For example, Communication Manager systems require circuit-switched trunks to access the PSTN because central offices today are not equipped for IP trunking. Some customers also prefer to continue to use their circuit-switched telephones in Communication Manager systems.

Circuit-switched endpoints interface to circuit packs that reside in media gateways or traditional port networks (PN). Although each media gateway belongs to one particular Network Region, no correlation exists between PNs and Network Regions. PNs are interconnected through a circuit-switched center stage or an ATM center stage (S8700 fiber-PNC systems) or an IP network (IP-PNC systems).

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