Ip Type Of Service And Differentiated Services; Alternate Gatekeepers; Checking Connections; Gateway Checks - 3Com NBX 100 Administrator's Manual

IP Type of Service and
Differentiated
Services
Alternate
Gatekeepers
Checking
Connections

Gateway Checks

External Call Control
Users of ConneXtions-equipped NBX systems can place H.323 calls to
other H.323 systems anywhere in the world without having to pay long
distance charges. Since there are no long distance charges for H.323
calls, there is no need to restrict them for cost reasons.
The header of each IP packet contains an 8-bit Type of Service (TOS) field
that indicates the precedence (relative importance) of the packet. Routers
then examine the TOS field and give precedence to packets with a higher
TOS setting.
Although your telephone system supports prioritization using the TOS
field, this facility is not supported for H.323 calls. However, for H.323 calls
over the WAN, routers can prioritize voice traffic using alternative means.
For example, during installation, you can select a range of UDP or TCP
port addresses to help with router setup.
A zone can contain only one gatekeeper at a time, although multiple
distinct devices can provide the gatekeeper function in a zone. Multiple
devices that provide the RAS signaling function for the gatekeeper are
called alternate gatekeepers. Each alternate gatekeeper appears to each
endpoint as a distinct Gatekeeper.
To ensure system availability, redundancy, and scalability, the gatekeeper
can provide RAS signaling function by using multiple physical or logical
devices, referred to as alternate gatekeepers.
You can use connection checks to pre-qualify an installation and to help
localize connection problems. H.323 gateway installers can conduct
connection checks for:
Gateway Checks
Network Checks
Gateway checks can verify that the NBX systems at each end of an H.323
connection are working properly.
Gateway Self-Check
A gateway self-check is simply an H.323 call that returns to the local
IP address (loopback test).

Checking Connections

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