H3C Technologies H3C S12500 Series Switches - Manual (Page 162)

148
Configuring the maximum number of attempts to send an NS
message for DAD
An interface sends an NS message for DAD after acquiring an IPv6 address. If the interface does not
receive a response within a specific time (determined by the ipv6 nd ns retrans-timer command), it
continues to send an NS message. If it still does not receive a response after the number of sent attempts
reaches the threshold (specified with the ipv6 nd dad attempts command), the acquired address is
considered usable.
To configure the attempts to send an NS message for DAD:
Step Command Remarks
1. Enter system view. system-view N/A
2. Enter interface view.
interface interface-type
interface-number
N/A
3. Configure the number of
attempts to send an NS
message for DAD.
ipv6 nd dad attempts value
Optional.
1 by default. When the value
argument is set to 0, DAD is
disabled.
Configuring ND snooping
Configuration preparation
Complete the following task before you configure ND snooping:
Execute the acl ipv6 enable command in system view.
For more information about the command acl ipv6 enable, see ACL and QoS Configuration References.
Introduction
The ND snooping feature is used in Layer 2 switching networks. It creates ND snooping entries using
DAD NS messages.
ND snooping entries are used to:
• Cooperate with the ND detection function. For more information about ND detection, see Security
Configuration Guide.
• Cooperate with the IP Source Guard function. For more information about IP Source Guard, see
Security Configuration Guide.
After you enable ND snooping on a VLAN of a switch, ND packets received by the interfaces of the
VLAN are redirected to the CPU. The CPU uses the ND packets to create or update ND snooping entries
comprising source IPv6 address, source MAC address, receiving VLAN, and receiving port information.
The following describes how an ND snooping entry is created, updated, and aged out.
1. Create an ND snooping entry.
The switch only uses received DAD NS messages to create ND snooping entries.
2. Update an ND snooping entry.