7-13
Software Configuration Guide—Release 15.0(2)SG
OL-23818-01
Chapter 7 Checking Port Status and Connectivity Configuring ICMP
To enable the sending of ICMP Redirect messages if the Cisco IOS software is forced to resend a packet
through the same interface on which it was received, enter the following command in interface
configuration mode:
Enabling ICMP Mask Reply Messages
Occasionally, network devices must know the subnet mask for a particular subnetwork in the
internetwork. To obtain this information, devices can send ICMP Mask Request messages. These
messages are responded to by ICMP Mask Reply messages from devices that have the requested
information. The Cisco IOS software can respond to ICMP Mask Request messages if the ICMP Mask
Reply function is enabled.
To have the Cisco IOS software respond to ICMP mask requests by sending ICMP Mask Reply
messages, enter the following command:
Command Purpose
Switch (config-if)# [no] ip redirects Enables ICMP Redirect messages.
Use the no keyword to disable the ICMP Redirect
messages and reduce CPU usage.
Command Purpose
Switch (config-if)# [no] ip mask-reply Enables response to ICMP destination mask requests.
Use the no keyword to disable this functionality.