Connection Considerations 475gateway. The remote gateway undoes the process and sends thedecompressed voice to an extension.Connection considerations apply to two areas:■ Overall Connectivity■ Quality of ServiceOverall Connectivity An end-to-end H.323 connection consists of a succession of PhysicalConnections and Logical Connections, both local and external.Physical ConnectionsAn H.323 gateway has few physical connections. An installer can add anH.323 gateway to an existing system by creating one physical connectionon the LAN that links a network interface card in an operating system toa hub or to a switch. The same connection also gives the H.323 gatewaya direct connection to every other device on the near-end LAN. Thosedevices include any 3Com Business or Basic Telephone, the Call Processor,and the firewall or router.Alternatively, you can use a second NIC in the gateway system to providea separate connection between the H.323 gateway and the IP router.Logical ConnectionsLocally, every device on an NBX LAN has the same physical access to thelocal network traffic as any other device. Consequently, addresses controlconnections because devices can only read information that is addressedto them. This makes addressing, and managing addresses, a key concernfor logical continuity.Logical continuity concerns extend throughout a network connectionbecause the identity of a frame (or packet) and its destination determinewhere it goes, how it is managed, and what happens to it.Because so many devices share the same physical media on the Internetand on the local network, there is always the possibility of incomplete ordegraded connections that arise from network congestion, deviceconfiguration, or addressing problems.Bridges, switches, routers, and firewalls can help to manage networkcongestion, conversions, and security. Configuration problems with ofany of these devices can cause connection difficulties.
