HP 6125XLG R2306-HP 6125XLG Blade Switch Layer 3 - IP Services Configuration G - Page 142

Enabling sending ICMPv6 redirect messages, Displaying and maintaining IPv6 basics

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• 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. If the device receives large numbers of malicious packets, its performance degrades greatly because it must send back ICMP Time Exceeded messages. To prevent such attacks, disable sending ICMPv6 Time Exceeded messages. To enable sending ICMPv6 time exceeded messages: Step 1. Enter system view. 2. Enable sending ICMPv6 time exceeded messages. Command system-view ipv6 hoplimit-expires enable Remarks N/A The default setting is disabled. Enabling sending ICMPv6 redirect messages Upon receiving a packet from a host, the device sends an ICMPv6 redirect message to inform a better next hop to the host when the following conditions are satisfied: • The interface receiving the packet is the interface forwarding the packet. • The selected route is not created or modified by any ICMPv6 redirect message. • The selected route is not a default route. • The forwarded packet does not contain the routing extension header. The ICMPv6 redirect function simplifies host management by enabling hosts that hold few routes to gradually optimize their routing table. However, to avoid adding too many routes on hosts, this function is disabled by default. To enable sending ICMPv6 redirect messages: Step 1. Enter system view. 2. Enable sending ICMPv6 redirect messages. Command system-view ipv6 redirects enable Remarks N/A By default, sending ICMPv6 redirect messages is disabled. Displaying and maintaining IPv6 basics Execute display commands in any view and reset commands in user view. Task Command Display IPv6 FIB entries. display ipv6 fib [ vpn-instance vpn-instance-name ] [ ipv6-address [ prefix-length ] ] Display the IPv6 information for the interface. display ipv6 interface [ interface-type [ interface-number ] ] [ brief ] Display the IPv6 prefix information for the interface. display ipv6 interface interface-type interface-number prefix 134

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134
•
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.
If the device receives large numbers of malicious packets, its performance degrades greatly because it
must send back ICMP Time Exceeded messages. To prevent such attacks, disable sending ICMPv6 Time
Exceeded messages.
To enable sending ICMPv6 time exceeded messages:
Step
Command
Remarks
1.
Enter system view.
system-view
N/A
2.
Enable sending ICMPv6 time
exceeded messages.
ipv6 hoplimit-expires enable
The default setting is disabled.
Enabling sending ICMPv6 redirect messages
Upon receiving a packet from a host, the device sends an ICMPv6 redirect message to inform a better
next hop to the host when the following conditions are satisfied:
•
The interface receiving the packet is the interface forwarding the packet.
•
The selected route is not created or modified by any ICMPv6 redirect message.
•
The selected route is not a default route.
•
The forwarded packet does not contain the routing extension header.
The ICMPv6 redirect function simplifies host management by enabling hosts that hold few routes to
gradually optimize their routing table. However, to avoid adding too many routes on hosts, this function
is disabled by default.
To enable sending ICMPv6 redirect messages:
Step
Command
Remarks
1.
Enter system view.
system-view
N/A
2.
Enable sending ICMPv6 redirect
messages.
ipv6 redirects enable
By default, sending ICMPv6
redirect messages is disabled.
Displaying and maintaining IPv6 basics
Execute
display
commands in any view and
reset
commands in user view.
Task
Command
Display IPv6 FIB entries.
display ipv6 fib
[
vpn-instance
vpn-instance-name
] [
ipv6-address
[
prefix-length
] ]
Display the IPv6 information for the
interface.
display ipv6 interface
[
interface-type
[
interface-number
] ] [
brief
]
Display the IPv6 prefix information for the
interface.
display ipv6 interface
interface-type interface-number
prefix