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Different video conferencing scenarios

The Codian MCU and IP VCR allow you to define a gateway and this H.323 gateway definition is used to

direct an outgoing call more specifically than just using an IP address. This means that the gateway definition

can often be used instead of a gatekeeper. Typical uses are:

 When the MCU calls an ISDN endpoint in to a conference, the gateway definition directs the call to the

ISDN gateway. The ISDN gateway interprets the second part of the calling address (a telephone

number in this case) and directs it to the ISDN endpoint.

 When the MCU calls the IP VCR in to a conference as described earlier in this chapter. The gateway is

needed because calling with the IP address only is ambiguous: the VCR can have several responses to an

incoming call depending on how it is set up. By using the gateway you can route the call directly to the

IP VCR’s recording port so the IP VCR will start recording the conference. The call address has two

parts: the IP address of the IP VCR and an “extension” that defines the port on the IP VCR.

The following diagram shows the MCU with the two H.323 gateways defined.

Figure 17: Video conferencing with gateway definitions

Video conferencing with a firewall

The MCU and IP VCR have an integral, optional firewall feature. This is designed to allow video calls to be

made between "internal" and "external" IP endpoints, as indicated in the figure “Overview of video

conferencing” on page 13.

This is quite different from a third party firewall which would typically be used for all traffic. If you want to

use your existing firewall and make calls between internal and external endpoints, then that firewall must

be "H.323 aware”.

For more information about both see Chapter 12‚ “Using firewalls”.

IP network

ISDN

ISDN Gateway

ISDN

endpoint

ISDN

MCU

IP VCR

endpoint

H.323 Gateway Definitions

IP VCR: IP address

ISDN GW: IP address

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Cisco ISDN GW 3241 Instrukcja Użytkownika Strona 29