Cisco 7604 Configuration Guide - Page 173

Chapter 8 Configuring IP Routing and DHCP Services Configuring Asymmetric Routing Support 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. Note The upstream and downstream routers must use one MAC address per VLAN and have different MAC 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 shows an example of using the asr-group command for asymmetric routing support in an Active/Active failover configuration. Figure 8-1 ASR Example with Active/Active Failover ISP A ISP B Context A interface Ethernet4 nameif outside asr-group 1 FWSM Failover/State link Context B interface Ethernet2 nameif outside asr-group 1 FWSM 132916 Outbound Traffic Return Traffic Inside network 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 OL-20748-01 Catalyst 6500 Series Switch and Cisco 7600 Series Router Firewall Services Module Configuration Guide using ASDM 8-31