Avaya Media Gateway G250, Administration Manual

Page: 333 / 840

Object tracking
Issue 5 June 2008 333
Typical application – interface backup via policy-based routing
In the previous typical application (see Typical application – backup for the WAN FastEthernet
interface on page 330), the
backup interface
command is used to specify a backup
interface. This typical application illustrates an alternative to the
backup interface
command, using policy-based routing (PBR) which configures a routing scheme for specified
traffic based on configured characteristics of the traffic. Thus, PBR can be used in combination
with object tracking to configure a backup mechanism for interfaces.
For an example that uses policy-based routing as an alternative to the
backup interface
command, replace the last four lines of the previous typical application with the example below.
The example creates a next hop list that sends the specified traffic to the WAN FastEthernet
interface, which is running PPPoE encapsulation. If the WAN FastEthernet interface becomes
unavailable, the next hop list routes the traffic to the Serial interface 3/1:1. PBR list 801 is
created and assigned to interface VLAN 1, so that traffic defined in PBR list 801 passing
through interface VLAN 1 is routed according to the next hop list.
Note:
Note:
You can define a static route over the WAN FastEthernet interface running DHCP
client. In such a case, the static route uses as the next hop the default router
learned from the DHCP server. This is useful for GRE tunnels which are defined
over the WAN Fast Ethernet running DHCP client. It is necessary to define static
routes in order to prevent loops. Therefore, the IP route command allows
configuration of static routes over WAN Fast Ethernet running DHCP client.