R21xx-HP FlexFabric 11900 Layer 3 IP Services Configuration Guide

142
Ste
p
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 not
enabled.
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 abnormally, disable the sending of
ICMPv6 destination unreachable messages to prevent attack risks.
To enable sending ICMPv6 destination unreachable messages:
Step Command Remarks
1. Enter system view.
system-view N/A
2. Enable sending ICMPv6 destination
unreachable messages.
ipv6 unreachables enable
By default, this function is
disabled.
Enabling sending ICMPv6 time exceeded messages
The device sends ICMPv6 Time Exceeded messages as follows:
• If a received packet is not destined for the device and its hop limit is 1, the device sends an ICMPv6
Hop Limit Exceeded message to the source.
• Upon receiving the first fragment of an IPv6 datagram destined for the device, the device starts a
timer. If the timer expires before all the fragments arrive, the device sends an ICMPv6 Fragment
Reassembly Timeout message to the source.