Cisco 7604 Configuration Guide - Page 172

Configuring Asymmetric Routing Support Chapter 8 Configuring IP Routing and DHCP Services Disabling Neighbor Change and Warning Message Logging By default neighbor change, and neighbor warning messages are logged. You can disable the logging of neighbor change message and neighbor warning messages. • To disable the logging of neighbor change messages, enter the following command in router configuration mode for the EIGRP routing process: hostname(config-router)# no eigrp log-neighbor-changes • To disable the logging of neighbor warning messages, enter the following command in router configuration mode for the EIGRP routing process: hostname(config-router)# no eigrp log-neighbor-warnings Configuring Asymmetric Routing Support In some situations, return traffic for a session may be routed through a different interface than it originated from. In failover configurations, return traffic for a connection that originated on one unit may return through the peer unit. This most commonly occurs when two interfaces on a single FWSM, or two FWSMs in a failover pair, are connected to different service providers and the outbound connection does not use a NAT address. By default, the FWSM drops the return traffic because there is no connection information for the traffic. You can prevent the return traffic from being dropped using the asr-group command on interfaces where this is likely to occur. When an interface configured with the asr-group command receives a packet for which it has no session information, it checks the session information for the other interfaces that are in the same group. Note In failover configurations, you must enable Stateful Failover for session information to be passed from the standby unit or failover group to the active unit or failover group. If it does not find a match, the packet is dropped. If it finds a match, then one of the following actions occurs: • If the incoming traffic originated on a peer unit in a failover configuration, some or all of the layer 2 header is rewritten and the packet is redirected to the other unit. This redirection continues as long as the session is active. • If the incoming traffic originated on a different interface on the same unit, some or all of the layer 2 header is rewritten and the packet is re-injected into the stream. This section contains the following topics: • Adding Interfaces to ASR Groups, page 8-31 • Asymmetric Routing Support Example, page 8-31 8-30 Catalyst 6500 Series Switch and Cisco 7600 Series Router Firewall Services Module Configuration Guide using ASDM OL-20748-01