Avaya G430 Manual page 261

static route to the branch office subnets accordingly. The username, password, and static
route can be configured in an external RADIUS/TACACS+ server.
• The RAS server can use OSPF to learn the branch office subnets. This is much simpler
to configure as all branch offices can share the same username and password. The
Branch Gateway is configured to advertise the branch office subnets with OSPF. This
feature requires the use of unnumbered IP addresses at the Branch Gateway and the
RAS. Since the Dialer and the primary interfaces are not expected to be up at the same
time, the RAS server can use passive-OSPF-interface and the Branch Gateway can use
static via routes.
• The Branch Gateway can call an ISP RAS (which is likely to assign it a dynamic IP
address) and open an IPSec VPN tunnel to an enterprise-owned VPN gateway.
While using OSPF and calling an ISP RAS are expected to be the most common scenarios,
they involve complex interaction with IP routing and the remote RAS server. For more detailed
configuration examples, see Application Note - VoIP Network Resiliency.
Prerequisites for configuring modem dial backup
• At least one dialer string, which determines the phone number(s) of the remote modem(s)
dialed by the Dialer interface
• A configured interface to be backed up
• Read/write or admin access level
• A modem: MultimodemUSB (MT5634ZBA-USB), or USRobotics USB modem (5637)
• RAS properties:
- A dialer string
- Authentication parameters (username, password, PAP/CHAP)
- IP addressing (static, dynamic, or unnumbered)
- Routing (static, RIP, or OSPF)
- IPSec VPN, with all necessary parameters configured
Note:
Make sure policy is configured properly at the RAS server to ensure that signaling has priority
over regular traffic.
For modem configuration instructions, see
Configuring modem dial backup
Procedure
1. From the general context, use the show interfaces USB-modem command to
Administering Avaya G430 Branch Gateway
verify that the modem is connected. You may be required to enable the modem.
Modems and the Branch Gateway
WAN interfaces
on page 247.
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