Disabling Icmp Error Message Sending; Displaying And Debugging Ip Performance - 3Com 7757 Configuration Manual

Disabling ICMP Error
Message Sending
Displaying and
Debugging IP
Performance
If you reference an ACL to filter directed broadcasts, only the directed broadcasts
that pass the ACL filtering can be forwarded to the directly connected network.
Table 79 Enable forwarding of directed broadcast packets
Operation
Enter system view
Enter VLAN interface view
Enable forwarding of
directed broadcast packets
to a directly connected
network
Sending error packets is the major function of the Internet Control Message
Protocol (ICMP). ICMP packets are usually sent by the network layer protocols or
transport layer protocols to notify corresponding devices of failures.
Although sending ICMP error packets facilitates network control and
management, it still has the following disadvantages:
Sending a lot of ICMP packets will increase network traffic.
■
If receiving a lot of malicious packets that cause a device to send ICMP error
■
packets, the device's performance will be reduced.
As the ICMP redirection function increases the routing table size of hosts, the
■
hosts' performance will be reduced if the routing table becomes very large.
If a host sends malicious ICMP destination unreachable packets, end users may
■
be affected.
To solve such problems, you can disable a device from sending ICMP error packets.
Currently, you can only disable the sending of ICMP redirect messages.
Table 80 Disable ICMP redirect message sending
Operation
Enter system view
Disable ICMP redirect
message sending
After the above configurations, you can execute the display command in any
view to display the running status to verify your IP performance configuration.

Disabling ICMP Error Message Sending

Command
system-view
interface interface-type
interface-number
ip forward-broadcast
[ acl-number ]
Command
system-view
undo icmp redirect send
Description
-
-
Required
By default, the switch does not
forward directed broadcast packets
to a directly connected network.
Description
-
Required
By default, the ICMP redirect
message sending is enabled.
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