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IP Routing Features
Configuring IP Parameters for Routing Switches
Disabling ICMP Destination Unreachable Messages
By default, when a ProCurve device receives an IP packet that the device
cannot deliver, the device sends an ICMP Unreachable message back to the
host that sent the packet. The following types of ICMP Unreachable messages
are generated:
■ Administration – The packet was dropped by the ProCurve device due to
a filter or ACL configured on the device.
■ Fragmentation-needed – The packet has the “Don’t Fragment” bit set in
the IP Flag field, but the ProCurve device cannot forward the packet
without fragmenting it.
■ Host – The destination network or subnet of the packet is directly
connected to the ProCurve device, but the host specified in the destination
IP address of the packet is not on the network.
■ Network – The ProCurve device cannot reach the network specified in
the destination IP address of the packet.
■ Port – The destination host does not have the destination TCP or UDP
port specified in the packet. In this case, the host sends the ICMP Port
Unreachable message to the ProCurve device, which in turn sends the
message to the host that sent the packet.
■ Protocol – The TCP or UDP protocol on the destination host is not
running. This message is different from the Port Unreachable message,
which indicates that the protocol is running on the host but the requested
protocol port is unavailable.
■ Source-route-failure – The device received a source-routed packet but
cannot locate the next-hop IP address indicated in the packet’s Source-
Route option.
Note Disabling an ICMP Unreachable message type does not change the ProCurve
device’s ability to forward packets. Disabling ICMP Unreachable messages
prevents the device from generating or forwarding the Unreachable messages.
To disable all ICMP Unreachable messages, enter the following command:
ProCurve(config)# no ip icmp unreachable
Syntax: [no] ip icmp unreachable
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