Enabling Sending Of Icmpv6 Destination Unreachable Messages - HP A5120 EI Series Configuration Manual

 Upon receiving the first fragment of an IPv6 datagram with the destination IP address being the
local address, the switch starts a timer. If the timer expires before all the fragments arrive, an
ICMPv6 Fragment Reassembly Timeout message is sent to the source.
If large amounts of malicious packets are received, the performance of the switch degrades greatly
because it has to send back ICMP Time Exceeded messages. You can disable sending of ICMPv6 Time
Exceeded messages.
Follow these steps to enable sending of ICMPv6 time exceeded messages:
To do...
Enter system view
Enable sending of ICMPv6 Time
Exceeded messages

Enabling sending of ICMPv6 destination unreachable messages

If the switch fails to forward a received IPv6 packet due to one of the following reasons, it drops the
packet and sends a corresponding ICMPv6 Destination Unreachable error message to the source.
If no route is available for forwarding the packet, the switch sends a "no route to destination"

ICMPv6 error message to the source.
If the switch fails to forward the packet due to administrative prohibition (such as a firewall filter or

an ACL), the switch sends the source a "destination network administratively prohibited" ICMPv6
error message.
If the switch fails to deliver the packet because the destination is beyond the scope of the source

IPv6 address (for example, the source IPv6 address of the packet is a link-local address whereas the
destination IPv6 address of the packet is a global unicast address), the switch sends the source a
"beyond scope of source address" ICMPv6 error message.
If the switch fails to resolve the corresponding link layer address of the destination IPv6 address, the

switch sends the source an "address unreachable" ICMPv6 error message.
If the packet with the destination being local and transport layer protocol being UDP and the

packet's destination port number does not match the running process, the switch sends the source a
"port unreachable" ICMPv6 error message.
If an attacker sends abnormal traffic that causes the switch to generate ICMPv6 destination unreachable
messages, end users may be affected. To prevent such attacks, you can disable the switch from sending
ICMPv6 destination unreachable messages.
Follow these steps to enable sending of ICMPv6 destination unreachable messages:
To do...
Enter system view
Enable sending of ICMPv6 destination
unreachable messages
Use the command...
system-view
ipv6 hoplimit-expires enable
Use the command...
system-view
ipv6 unreachables enable
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Remarks
—
Optional
Enabled by default.
Remarks
—
Required
Disabled by default.