Brocade FastIron Ethernet Switch Layer 3 Routing Configuration Guide - Manual (Page 182)

NOTE
IPv6 is disabled by default in the router code and must be configured on each interface that will
support IPv6.
IPv6 ICMP feature configuration
As with the Internet Control Message Protocol (ICMP) for IPv4, ICMP for IPv6 provides error and
informational messages. Implementation of the stateless auto configuration, neighbor discovery, and
path MTU discovery features use ICMP messages.
This section explains how to configure following IPv6 ICMP features:
• ICMP rate limiting
• ICMP redirects
Configuring ICMP rate limiting
You can limit the rate at which IPv6 ICMP error messages are sent out on a network. IPv6 ICMP
implements a token bucket algorithm.
To illustrate how this algorithm works, imagine a virtual bucket that contains a number of tokens. Each
token represents the ability to send one ICMP error message. Tokens are placed in the bucket at a
specified interval until the maximum number of tokens allowed in the bucket is reached. For each error
message that ICMP sends, a token is removed from the bucket. If ICMP generates a series of error
messages, messages can be sent until the bucket is empty. If the bucket is empty of tokens, error
messages cannot be sent until a new token is placed in the bucket.
You can adjust the following elements related to the token bucket algorithm:
• The interval at which tokens are added to the bucket. The default is 100 milliseconds.
• The maximum number of tokens in the bucket. The default is 10 tokens.
For example, to adjust the interval to 1000 milliseconds and the number of tokens to 100 tokens, enter
the following command.
device(config)# ipv6 icmp error-interval 1000 100
Syntax: ipv6 icmp error-interval interval [ number-of-tokens ]
The interval in milliseconds at which tokens are placed in the bucket can range from 0 - 2147483647.
The maximum number of tokens stored in the bucket can range from 1 - 200.
NOTE
If you retain the default interval value or explicitly set the value to 100 milliseconds, output from the
show run command does not include the setting of the ipv6 icmp error-interval command because
the setting is the default.Also, if you configure the interval value to a number that does not evenly
divide into 100000 (100 milliseconds), the system rounds up the value to a next higher value that does
divide evenly into 100000. For example, if you specify an interval value of 150, the system rounds up
the value to 200.
ICMP rate limiting is enabled by default. To disable ICMP rate limiting, set the interval to zero.
IPv6 ICMP feature configuration
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