Brocade FastIron Ethernet Switch Layer 3 Routing Configuration Guide - Manual (Page 63)

• 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 Brocade 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 Source-Route option.
You can disable the Brocade device from sending these types of ICMP messages on an individual
basis. To do so, use the following CLI method.
NOTE
Disabling an ICMP Unreachable message type does not change the Brocade device 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 no ip icmp unreachable command.
device(config)# no ip icmp unreachable
Syntax: [no] ip icmp unreachable { host | protocol | administration | fragmentation-needed | port |
source-route-fail }
• If you enter the command without specifying a message type (as in the example above), all types of
ICMP Unreachable messages listed above are disabled. If you want to disable only specific types of
ICMP Unreachable messages, you can specify the message type. To disable more than one type of
ICMP message, enter the no ip icmp unreachable command for each messages type.
• The administration parameter disables ICMP Unreachable (caused by Administration action)
messages.
• The fragmentation-needed parameter disables ICMP Fragmentation-Needed But Do not-Fragment
Bit Set messages.
• The host parameter disables ICMP Host Unreachable messages.
• The port parameter disables ICMP Port Unreachable messages.
• The protocol parameter disables ICMP Protocol Unreachable messages.
• The source-route-fail parameter disables ICMP Unreachable (caused by Source-Route-Failure)
messages.
To disable ICMP Host Unreachable messages but leave the other types of ICMP Unreachable
messages enabled, enter the following commands instead of the command shown above.
device(config)# no ip icmp unreachable host
If you have disabled all ICMP Unreachable message types but you want to re-enable certain types, for
example ICMP Host Unreachable messages, you can do so by entering the following command.
device(config)# ip icmp unreachable host
Enabling ICMP Redirect Messages
You can enable and disable IPv4 ICMP redirect messages globally or on individual Virtual Ethernet (VE)
interfaces but not on individual physical interfaces.
Enabling ICMP Redirect Messages
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