Avaya G250 Administration page 168

Configuring WAN interfaces
ICMP keepalive is a mechanism that reports on the status of an IP address and its next hop.
The destination interface is only declared to be alive if the next hop is also reachable. This
feature is critical for mechanisms such as policy-based routing that must guarantee service on a
particular path.
Figure 17: G250/G350 with T1 and xDSL lines
Headquarters
For example, your branch office may have a G250 or G350 that connects to the Headquarters
over a T1 line and via an xDSL connection to the Internet. The T1 line is used for voice traffic,
while data packets are sent over the xDSL line. Normal keepalive cannot report on the status of
the entire WAN path. If the FastEthernet line protocol is up but the xDSL connected to it is
down, normal keepalive reports that the Fast Ethernet interface is up. Only ICMP keepalive,
which checks the next hop, correctly reports that the WAN path is down. Policy-based routing,
which relies on the interface status to determine how packets are routed, can use ICMP
keepalive to know the status of the interfaces on its next hop list.
Note:
ICMP keepalive is not used with a GRE tunnel interface. The GRE tunnel has its
Note:
own keepalive mechanism. For details, see
page 321.
Note:
You cannot configure both DHCP Client and ICMP keepalive on the WAN Fast
Note:
Ethernet interface. For details on DHCP Client see
page 95.
Use the keepalive-icmp command in the context of the interface to enable the ICMP
keepalive feature. Use the no form of this command to deactivate the feature.
The keepalive-icmp command includes the following parameters:
destination ip address — the destination IP address for the keepalive packets.
●
next hop MAC address — the next hop MAC address for the keepalive packets. This
●
parameter is only relevant for the WAN Fast Ethernet port.
168 Administration for the Avaya G250 and Avaya G350 Media Gateways
Router
2 x T1/E1 or USP WAN Module
G250/G350
ISP
xDSL1
Hub/Switch
Small Branch
Configuring GRE tunneling
Configuring DHCP client
Voice
Vlan1
DSCP
S8300
Data
Vlan2
DSCP
on
on