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Overview of the Cisco IOS Gatekeeper

Overview of the Cisco IOS Gatekeeper

Cisco offers a Voice over IP gatekeeper called the Multimedia Conference Manager, which is an H.323-compliant program implemented as part of the Cisco IOS software. The Multimedia Conference Manager software can run on Cisco 2500, 2600, 3600, and 3810 routers.

The following sections describe the main functions of a gatekeeper, which are supported by Cisco's Multimedia Conference Manager:

Zone and Subnet Configuration

A zone is defined as the set of H.323 nodes controlled by a single gatekeeper. Gatekeepers co-existing on a network can be configured so that they register endpoints from different subnets.

Endpoints attempt to discover a gatekeeper, and consequently what zone they are members of, using the RAS message protocol. The protocol supports a discovery message that may be sent multicast or unicast.

If the message is sent multicast, the endpoint registers non-deterministically with the first gatekeeper to respond. Any endpoint on a subnet that is not enabled for the gatekeeper will not be accepted as a member of that gatekeeper's zone. If the gatekeeper receives a discovery message from such an endpoint, it will send an explicit reject message.

Terminal Name Registration

Gatekeepers recognize one of three types of terminal aliases, or terminal names:

If an H.323 network deploys inter-zone communication, each terminal should at least have a fully-qualified e-mail name as its H.323 ID. For example, bob@cisco.com. The domain name of the e-mail ID should be the same as the configured domain name for the gatekeeper of which it is to be a member. As in the previous example, the domain name would be cisco.com.

Inter-Zone Communication

To allow endpoints to communicate between zones, gatekeepers must be able to determine which zone an endpoint is in and locate the gatekeeper responsible for that zone. If DNS is available, you can associate a DNS domain name to each gatekeeper.

Accounting via RADIUS/TACACS+

If you enable AAA on the gatekeeper, the gatekeeper will emit an accounting record each time an endpoint registers or unregisters, or each time a call is admitted or disconnected.

Inter-Zone Routing

There are three types of address destinations used in H.323 calls. The destination can be specified using either an H.323-ID address (a character string), an E.164 address (a string containing telephone keypad characters), or an e-mail ID (a character string). The way inter-zone calls are routed by the Cisco IOS Gatekeeper depends on the type of address being used.


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Posted: Fri Sep 27 04:52:59 PDT 2002
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