Disabling Forwarding Icmp Fragments; Configuring Rate Limit For Icmp Error Messages; Specifying The Source Address For Icmp Packets - HP 6125XLG Layer 3-Ip Services Configuration Manual

Sending ICMP error messages facilitates network management, but sending excessive ICMP messages
increases network traffic. A device's performance degrades if it receives a lot of malicious ICMP
messages that cause it to respond with ICMP error messages.
To prevent such problems, you can disable the device from sending ICMP error messages. A device that
is disabled from sending ICMP time-exceeded messages does not send ICMP TTL Expired messages.
However, it can still send ICMP Fragment Reassembly Timeout messages.

Disabling forwarding ICMP fragments

Disabling forwarding ICMP fragments can protect your device from ICMP fragments attacks.
To disable forwarding ICMP fragments:
Step
1. Enter system view.
2. Disable forwarding ICMP fragments.

Configuring rate limit for ICMP error messages

To avoid sending excessive ICMP error messages within a short period that might cause network
congestion, you can limit the rate at which ICMP error messages are sent. A token bucket algorithm is
used with one token representing one ICMP error message. Tokens are placed in the bucket at a specific
interval until the maximum number of tokens that the bucket can hold is reached. Tokens are removed
from the bucket when ICMP error messages are sent. When the bucket is empty, ICMP error messages
are not sent until a new token is placed in the bucket.
To configure rate limit for ICMP error messages:
Step
1. Enter system view.
2. Set the interval and bucket
size for ICMP error
messages

Specifying the source address for ICMP packets

Perform this task to specify the source IP address for outgoing ping echo request and ICMP error
messages. HP recommends that you specify the IP address of the loopback interface as the source IP
address. This feature helps users to locate the sending device easily.
If you specify an IP address in the ping command, ping echo requests use the specified address as the
source IP address rather than the IP address specified by the ip icmp source command.
Command
system-view
ip icmp fragment discarding
Command
system-view
ip icmp error-interval
milliseconds [ bucketsize ]
126
Remarks
N/A
By default, forwarding ICMP
fragments is enabled.
Remarks
N/A
By default, the bucket allows a maximum
of 10 tokens, and tokens are placed in
the bucket at the interval of 100
milliseconds.
To disable the ICMP rate limit, set the
interval to 0 milliseconds.