H3C Technologies H3C S12500 Series Switches - Manual (Page 163)

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Upon receiving an ND packet, the switch 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 switch does
not update the entry. If the entry is not refreshed for more than one second, the switch 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
switch performs active acknowledgement.
The active acknowledgement process is as follows:
{
The switch checks the validity of the existing ND snooping entry. The switch 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 one second 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 switch 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 switch performs active acknowledgement as follows:
The switch sends out a DAD NS message including the IPv6 address of the ND snooping entry.
{
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
To configure ND snooping:
Step Command Remarks
1. Enter system view. system-view N/A
2. Enter VLAN view. vlan vlan-id N/A
3. Enable ND snooping. ipv6 nd snooping enable Disabled by default.
4. Return to system view. quit N/A
5. Enter Layer 2 Ethernet interface
view/Layer 2 aggregate interface
view.
interface interface-type
interface-number
N/A