H3C Technologies H3C S5560 Series Switches - Manual (Page 173)

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Tokens are removed from the bucket when ICMPv6 error messages are sent. When the bucket is empty,
ICMPv6 error messages are not sent until a new token is placed in the bucket.
To configure the rate limit for ICMPv6 error messages:
Step Command Remarks
1. Enter system view. system-view N/A
2. Set the bucket size and the
interval for tokens to arrive in
the bucket for ICMPv6 error
messages
ipv6 icmpv6 error-interval
milliseconds [ bucketsize ]
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 ICMPv6 rate limit,
set the interval to 0 milliseconds.
Enabling replying to multicast echo requests
The device does not respond to multicast echo requests by default. In some scenarios, however, you must
enable the device to answer multicast echo requests so the source host can obtain needed information.
To enable the device to answer multicast echo requests:
Step Command Remarks
1. Enter system view. system-view N/A
2. Enable replying to multicast
echo requests.
ipv6 icmpv6 multicast-echo-reply
enable
By default, this function is disabled.
Enabling sending ICMPv6 destination unreachable messages
The device sends ICMPv6 destination unreachable messages as follows:
• If a packet does not match any route, the device sends a No Route to Destination ICMPv6 error
message to the source.
• If the device fails to forward the packet because of administrative prohibition (such as a firewall
filter or an ACL), the device sends the source a Destination Network Administratively Prohibited
ICMPv6 error message.
• If the device fails to deliver the packet because the destination is beyond the scope of the source
IPv6 address (for example, the source IPv6 address is a link-local address whereas the destination
IPv6 address is a global unicast address), the device sends the source a Beyond Scope of Source
Address ICMPv6 error message.
• If the device fails to resolve the link layer address for the destination IPv6 address, the device sends
the source an Address Unreachable ICMPv6 error message.
• If a UDP packet received is destined for the device but its UDP destination port number does not
match any process, the device sends the source a Port Unreachable ICMPv6 error message.
If a device is generating ICMPv6 destination unreachable messages incorrectly, disable the sending of
ICMPv6 destination unreachable messages to prevent attack risks.
To enable sending ICMPv6 destination unreachable messages: