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Catalyst 6500 Series Switch Command Reference—Release8.1
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Chapter2 Catalyst 6500 Series Switch and ROM Monitor Commands set ip unreachable
set ip unreachable
To enable or disable ICMP unreachable messages on the Catalyst 6500 series switch, use the set ip
unreachable command.
set ip unreachable {enable | disable}
Syntax Description
Defaults The default is ICMP unreachable messages is enabled.
Command Types Switch command.
Command Modes Privileged.
Usage Guidelines W h en y ou en a ble I CM P u nreachable messages, the switch returns an ICMP unreachable message to the
source host whenever it receives an IP datagram that it cannot deliver. When you disable ICMP
unreachable messages, the switch does not notify the source host when it receives an IP datagr am tha t it
cannot deliver.
For example, a switch has the ICMP unreachable message function enabled and IP fragmentation
disabled. If a FDDI frame is received and needs to transmit to an Ethernet port, the switch cannot
fragment the packet. The switch drops the packet and returns an IP unreachable message to the Internet
source host.
Examples This example shows how to disable ICMP unreachable messages:
Console> (enable) set ip unreachable disable
ICMP Unreachable message disabled.
Console> (enable)
Related Commands show ip route
enable Allows IP unreachable messages to be returned to the source host.
disable Prevents IP unreachable messages from being returned to the source
host.