H3C Technologies H3C WX3000E Series Wireless Switches - Manual (Page 128)

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2. Updating an ND snooping entry
Upon receiving an ND packet, the device searches the ND snooping table for an entry containing the
source IPv6 address of the packet. If the entry was refreshed within one second, the device does not
update the entry. If the entry is not refreshed for more than one second, the device matches the MAC
address of the ND packet and the receiving port against that in the entry.
• If both of them match those in the entry, the device updates the aging time of the ND snooping
entry.
• If neither of them matches the entry and the received packet is a DAD NS message, the message is
ignored.
• If neither of them matches the entry and the received packet is not a DAD NS message, the device
performs active acknowledgement.
The active acknowledgement is performed in the following steps.
• The device checks the validity of the existing ND snooping entry. The device sends out a DAD NS
message including the IPv6 address of the ND snooping entry. If a corresponding NA message
(whose source IPv6 address, source MAC address, receiving port, and source VLAN are consistent
with those of the existing entry) is received, the device updates the aging time of the existing entry.
If no corresponding NA message is received within five seconds after the DAD NS message is sent,
the device starts to check the validity of the received ND packet.
• To check the validity of the received ND packet (packet A for example), the device sends out a DAD
NS message including the source IPv6 address of packet A. If a corresponding NA message
(whose source IPv6 address, source MAC address, receiving port, and source VLAN are consistent
with those of packet A) is received, the device updates the aging time of the entry. If no
corresponding NA message is received within one second after the DAD NS message is sent, the
device does not update the entry.
3. Aging out an ND snooping entry
An ND snooping entry is aged out after 25 minutes. If an ND snooping entry is not updated within 15
minutes, the device performs active acknowledgement.
The device sends out a DAD NS message including the IPv6 address of the ND snooping every one
second.
• If a corresponding NA message is received (the source IPv6 address, source MAC address,
receiving port, and source VLAN are consistent with those of the existing entry), the device updates
the aging time of the existing entry.
• If no corresponding NA message is received within one second after the DAD NS message is sent
out, the device removes the entry when the timer expires.
Configuration procedure
Follow these steps to configure ND snooping:
To do… Use the command… Remarks
Enter system view system-view —
Enter VLAN view vlan vlan-id —
Enable ND snooping ipv6 nd snooping enable
Required
Disabled by default.
Return to system view quit —