Avaya 555-245-600 manual IP-TDM-IP connectivity, Hairpinning, Shuffling

Resource sizing

Although we stated that calls between two circuit-switched endpoints on different port networks use an IP connection, the use of a circuit-switched center stage between the two PNs is also supported. However, using circuit-switched facilities is not viable for interconnecting multiple Media Gateways, or for interconnecting PNs and Media Gateways.

Figure 65 provides some insight into how a call between an IP endpoint and a circuit-switched endpoint, as well as a call between two circuit-switched endpoints, utilizes media processing and TDM resources. Calls between IP endpoints are addressed first.

Communication Manager supports three general modes of connectivity between IP endpoints: IP-TDM-IPconnectivity, hairpinning, and shuffling. Hairpinning can take one of two forms: deep or shallow. These various modes of connectivity are described in more detail below.

IP-TDM-IP connectivity

A call that uses IP-TDM-IP connectivity between two IP endpoints requires one bidirectional media processing “channel” for each IP endpoint involved, as well as a bidirectional TDM resource on every PN (or Media Gateway) that is involved in the call. This option most often applies in systems that use a circuit-switched center stage for interport network connectivity. In such a system, IP-TDM-IP is required in order for two IP endpoints in network regions not configured for connectivity (in the sense of the IRCM matrix) to talk to one another.

Hairpinning

Unlike the IP-TDM-IP connectivity option, hairpinning requires that all media processing resources for a given call reside on a single TN2302AP or TN2602AP media processing circuit pack or a single G350 or G700 Media Gateway VoIP Media Module. A hairpinned call is originally set up as an IP-TDM-IP call, but once the set-up process is complete, no TDM resources are required. However, resources on the Media Processing circuit pack or VoIP Media Module are required for the duration of the call. A Media Processing circuit pack and a VoIP Media Module each house an onboard Central Processing Unit (CPU) and Digital Signal Processors (DSPs).

Shuffling

A shuffled call relinquishes all TDM and media processing resources after call setup. Therefore, the media stream of a shuffled call traverses only an IP network. This is the most commonly used mode of connectivity between two IP endpoints in the same system.

Figure 66: Connectivity modes between two IP endpoints on page 202 shows the various modes of connectivity between two IP endpoints.

Issue 6 January 2008 201