H3C Technologies H3C SecPath F1000-E - Manual (Page 122)

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Configuring ICMPv6 Packet Sending
Configuring the Maximum ICMPv6 Error Packets Sent in an
Interval
If too many ICMPv6 error packets are sent within a short time in a network, network congestion may
occur. To avoid network congestion, you can control the maximum number of ICMPv6 error packets sent
within a specified time by adopting the token bucket algorithm.
You can set the capacity of a token bucket to determine the number of tokens in the bucket. In addition,
you can set the update interval of the token bucket, that is, the interval for restoring the configured
capacity. One token allows one ICMPv6 error packet to be sent. Each time an ICMPv6 error packet is
sent, the number of tokens in a token bucket decreases by one. If the number of ICMPv6 error packets
successively sent exceeds the capacity of the token bucket, the additional ICMPv6 error packets cannot
be sent out until the capacity of the token bucket is restored.
Follow these steps to configure the capacity and update interval of the token bucket:
To do… Use the command… Remarks
Enter system view system-view —
Configure the capacity
and update interval of
the token bucket
ipv6 icmp-error { bucket
bucket-size | ratelimit
interval } *
Optional
By default, the capacity of a token bucket is 10 and
the update interval is 100 milliseconds. In other
words, at most 10 ICMPv6 error packets can be
sent within 100 milliseconds.
The update interval “0” indicates that the number
of ICMPv6 error packets sent is not restricted.
Enabling Replying to Multicast Echo Requests
If hosts are configured to answer multicast echo requests, an attacker may use this mechanism to attack
a host. For example, if Host A (an attacker) sends an echo request with the source being Host B to a
multicast address, all the hosts in the multicast group will send echo replies to Host B. Therefore, to
prevent such an attack, a device is disabled from replying multicast echo requests by default.
Follow these steps to enable replying to multicast echo requests:
To do… Use the command… Remarks
Enter system view system-view —
Enable replying to multicast echo
requests ipv6 icmpv6
multicast-echo-reply enable
Required
Disabled by default.
Enabling Sending of ICMPv6 Time Exceeded Messages
A device sends out an ICMPv6 Time Exceeded message in the following cases: