Adding Interfaces To Asr Groups; Asymmetric Routing Support Example - Cisco 7604 Configuration Manual

Chapter 8 Configuring IP Routing and DHCP Services

Adding Interfaces to ASR Groups

Enter the following commands to add an interface to an asymmetric routing group. Stateful Failover
must be enabled for asymmetric routing support to function properly between units in failover
configurations.
hostname/ctx1(config)# interface if
hostname/ctx1(config-if)# asr-group num
Valid values for num range from 1 to 32. You need to enter the command for each interface that will
participate in the ASR group. You can create up to 32 ASR groups and assign a maximum of 8 interfaces
to each group.
The upstream and downstream routers must use one MAC address per VLAN and have different MAC
Note
addresses for different VLANs to allow for the redirection of packets from a standby unit to an active
unit in failover configurations.

Asymmetric Routing Support Example

Figure 8-1
Active/Active failover configuration.
Figure 8-1
Context A
interface Ethernet4
nameif outside
asr-group 1
Context A is active on one unit and context B is active on the other. Each context has an interface named
"outside", both of which are configured as part of asr-group 1. The outbound traffic is routed through
the unit where context A is active. However, the return traffic is being routed through the unit where
context B is active. Normally, the return traffic would be dropped because there is no session information
Catalyst 6500 Series Switch and Cisco 7600 Series Router Firewall Services Module Configuration Guide using ASDM
OL-20748-01
shows an example of using the asr-group command for asymmetric routing support in an
ASR Example with Active/Active Failover
ISP A
Failover/State link
FWSM
Outbound Traffic
Return Traffic
network
ISP B
interface Ethernet2
FWSM
Inside
Configuring Asymmetric Routing Support
Context B
nameif outside
asr-group 1
8-31