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Software Configuration Guide—Release 12.2(25)SG
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Chapter5 Checking Port Status and Conne ctivity
Configuring ICMP
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 m essages 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, perform this task:
Command Purpose
Switch (config-if)# [no] ip mask-reply Enables response to ICMP destination mask requests.
Use the no keyword to disable this functionality.