Dell FCX624-S Laptop User Manual


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818 PowerConnect B-Series FCX Configuration Guide
53-1002266-01
Configuring IP parameters – Layer 3 Switches
26
Disabling replies to broadcast ping requests
By default, Dell PowerConnect devices are enabled to respond to broadcast ICMP echo packets,
which are ping requests.
To disable response to broadcast ICMP echo packets (ping requests), enter the following command.
PowerConnect(config)# no ip icmp echo broadcast-request
Syntax: [no] ip icmp echo broadcast-request
If you need to re-enable response to ping requests, enter the following command.
PowerConnect(config)# ip icmp echo broadcast-request
Disabling ICMP destination unreachable messages
By default, when a Dell PowerConnect 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. You can
selectively disable a Dell PowerConnect device response to the following types of ICMP
Unreachable messages:
Administration – The packet was dropped by the Dell PowerConnect device due to a filter or
ACL configured on the device.
Fragmentation-needed – The packet has the Do not Fragment bit set in the IP Flag field, but
the Dell PowerConnect device cannot forward the packet without fragmenting it.
Host – The destination network or subnet of the packet is directly connected to the Dell
PowerConnect device, but the host specified in the destination IP address of the packet is not
on the network.
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 Dell
PowerConnect 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 Dell PowerConnect 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 Dell PowerConnect 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 following command.
PowerConnect(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.