Avaya Media Gateway G250, Administration Manual

Page: 300 / 840

Configuring WAN interfaces
300 Administration for the Avaya G250 and Avaya G350 Media Gateways
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Dynamic CAC can be used in conjunction with IGAR to provide a stable backup path for
continued IP phone function in the event of a dial backup scenario. Dynamic CAC notifies
the Avaya Communication Manager server that no bandwidth is available for bearer traffic,
keeping the dial circuit from becoming fully congested. IGAR provides a path for
gateway-to-gateway traffic destined for a remote Avaya Communication Manager server
by forcing voice calls to and from the branch office to use the PSTN for bearer traffic. For
more information on configuring Dynamic CAC, see
Dynamic CAC on page 317. For more
information on configuring IGAR, see Administrator Guide for Avaya Communication
Manager , 03-300509.
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Static IP addressing for the Dialer interface may not be feasible. Dynamic IP addressing is
available to enable you to connect to the remote network through an ISP. ISPs commonly
provide IP addressing for connected ports on an as-needed basis. IP unnumbered links
are available to supply addressing in situations where you wish to run routing over your
network link without committing a subnet. For information on configuring dynamic IP
addressing, see
Using dynamic local peer IP on page 582. For information on configuring
unnumbered IP, see Configuring unnumbered IP interfaces on page 492.
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Object tracking can be used with the Loopback interface to provide an alternative method
for activating the Dialer interface when connectivity with the main office is lost. This is
useful in configurations where the WAN interface is not connected directly to the
G250/G350. Use object tracking to configure RTRs to verify connectivity with the main
office. If the RTR fails, the object tracker can be configured to change the status of the
Loopback interface to down. If the Dialer interface is configured as the backup for the
Loopback interface, the Dialer interface will automatically dial when connectivity fails. For
more information about object tracking, see
Object tracking on page 319.
Note:
Note:
In a situation where the same modem is used for inbound Avaya Service calls
and outbound dial backup calls, only one call can be active at any time.
Note:
Note:
Refer to www.multitech.com for a listing of modem AT commands used to
configure the modem directly.
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You must disable modem dial backup before configuring FIPS.
Configuration example
This example sets up a modem dial backup for the WAN link between a branch office and the
headquarters data center. The branch office is connected to the corporate network using a
G250/G350. IP phone users in the branch office connect to an MGC located in the headquarters
data center, and an RAS is located in the headquarters data center, with multiple phone lines
available for dial access. The primary WAN connection is a PPP link connected to the port serial
3/1. The Dialer PPP session uses CHAP encryption. The corporate network is routed using
OSPF. An analog trunk connects the branch office to the PSTN for non-corporate bearer traffic.