VTEL WG500, Руководство по установке

Страница: 10 / 104

Installation Guide
Chapter 1. Videoconferencing Basics 1.2
H.323 IDs
One potential problem is that not all computers have access to all aliases, but a solution
has already been devised. An alias, known to the videoconferencing system used when
making LAN based calls, is called an H.323 ID. It looks like an IP alias and works the
same way, but is administered and only used by the videoconferencing system. It is a
good idea to make your IP alias and your H.323 ID the same.
E.164 addresses
Another technique for LAN addressing is to assign a number to each system. This
number looks like a phone number, and therefore contains only digits and the * and #
symbols. This number is known as an E.164 address.
Gatekeepers
Videoconferencing looks better with more bandwidth given to it. However, bandwidth
is limited, and if all the bandwidth in a LAN is used for videoconferencing, the other
computer applications will suffer. In order to limit the amount of bandwidth used for
videoconferencing, many corporations are installing gatekeepers. A gatekeeper is
another node on the Ethernet that simply keeps track of how many calls are currently
active and limits new calls accordingly. When setting up a new videoconferencing
system, such as a WG500, the system must be aware of any gatekeepers on the LAN. A
gatekeeper is optional, or there could be many in a large system.
Part of the WG500 setup process is to indicate to the video-conferencing system which
gatekeeper, if any, it is to use (see Chapter 3). The gatekeeper can also help with the
address translations and is, in fact, where the H.323 IDs and E.164 addresses get
converted to IP addresses.
Gateways
A LAN-based (H.323) system can call a WAN-based (H.320) system but there needs to
be something to make the protocol translation—a gateway. That same gateway can be
used to accept an incoming call from a WAN-based system via the phone lines and
route that call to a LAN-based system using the company-wide Ethernet.
The gateway complicates the call only in that the phone number must include the phone
number of the WAN device as well as the LAN address of the LAN device. Therefore
the dialing procedure is slightly more complex. See Chapter 4, “Using the Connection
Interface window.”
There are several manufacturers of gateways and your WG500 system must know the
address and the manufacturer of the gateway(s) it is to use. This information will be
entered into the Advanced Configuration program (see Chapter 3).