savi max dad-delay

Function

The savi max dad-delay command sets the time for listening to an NA packet responding to address conflicts.

The undo savi max dad-delay command restores the default setting.

By default, the time for listening to an NA packet responding to address conflicts is 2 seconds.

Format

savi max dad-delay value

undo savi max dad-delay

Parameters

Parameter	Description	Value
value	Specifies the time for listening to an NA packet responding to address conflicts.	The value is an integer that ranges from 1 to 100, in seconds.

Views

System view

Default Level

2: Configuration level

Usage Guidelines

Usage Scenario

The savi max dad-delay command is applicable only for SLAAC-Only scenarios and DHCPv6+SLAAC scenarios.

In SLAAC-Only scenarios:

When obtaining an IP address in SLAAC mode, an ND client generates the IPv6 address based on the prefix in the RA packet. After the IPv6 address is generated, the ND client sends an NS packet to check whether duplicate addresses exist on the network. When detecting the NS packet in the DAD process from the ND client, the device generates an ND snooping entry, sets the entry to the detect state, and listens to the mapping NA packet.
- If a mapping NA packet is detected in the configured listening period, IPv6 address conflict occurs and the device deletes this ND snooping entry.
- If no mapping NA packet is detected in the configured listening period, the IPv6 address is available and the device sets the ND snooping entry to the bound state. The device deletes the ND snooping entry only when the entry ages out. If automatic user status detection for users mapping ND snooping dynamic binding entries is enabled using the nd user-bind detect enable command on the device, and no NA packet is returned from the user after NS packets are sent for times configured using the nd user-bind detect retransmit retransmit-times interval retransmit-interval command, the device considers the user to be offline and deletes the mapping ND snooping entry.
In DHCPv6+SLAAC scenarios:
- The procedure for processing packets by SAVI in SLAAC mode is the same as that in SLAAC-Only scenarios.
- When obtaining an IP address in DHCPv6 mode, a DHCPv6 client may send an NS packet to check whether duplicate addresses exist on the network. When detecting the NS packet in the DAD process from the DHCPv6 client, the device sets the mapping DHCPv6 snooping entry to the detect state, and listens to the mapping NA packet.
  - If a mapping NA packet is detected in the configured listening period, IPv6 address conflict occurs and the device deletes this DHCPv6 snooping entry.
  - If no mapping NA packet is detected in the configured listening period, the IPv6 address is available and the device sets the DHCPv6 snooping entry to the bound state.
  When the DHCPv6 Snooping entry is in detection state, the device deletes this entry after detecting the NA packets within the time of listening on NA packets with response address conflicts. When the DHCPv6 Snooping entry is in bound state, the device deletes this entry after detecting the DHCPv6 Decline or DHCPv6 Release packets sent from the DHCPv6 clients.

Prerequisites

The SAVI function has been enabled using the savi enable command.

Precautions

This command is used together with ND snooping and DHCPv6 snooping.

Example

# Set the time for listening to an NA packet responding to address conflicts to 5 seconds.

<HUAWEI> system-view
[HUAWEI] savi enable 
[HUAWEI] savi max dad-delay 5