an H.323-compliant program implemented as part of the Cisco IOS software. The following
sections describe the main functions of a gatekeeper:
coexist 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 nondeterministically
with the first gatekeeper to respond. Any endpoint on a subnet that is not enabled for the
gatekeeper is not accepted as a member of that gatekeeper's zone. If the gatekeeper receives a
discovery message from such an endpoint, it sends an explicit reject message.
fully qualified e-mail name as its H.323 ID, such as ccdp@ciscopress.com. The domain name
of the e-mail ID should be the same as the configured domain name for the gatekeeper of which
it will be a member. The domain name would be ciscopress.com.
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. If AAA is enabled on the
gatekeeper, the gatekeeper emits an accounting record each time an endpoint registers or
unregisters, or each time a call is admitted or disconnected.
using 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). How interzone calls are routed by the
Cisco IOS gatekeeper depends on the type of address being used.
For example, to resolve the domain name ccdp@ciscopress.com, the source endpoint's
gatekeeper finds the gatekeeper for ciscopress.com and sends the location request for