Configuring Manually Triggered Dual-Device ND Hot Backup

This section describes how to enable dual-device ND hot backup to back up ND entries between devices. This allows fast service switching if a network node or link fails, enhancing service reliability.

Prerequisites

Before configuring manually triggered dual-device ND hot backup, ensure that the same ND configuration has been performed on the master and backup devices. Otherwise, downstream traffic may be interrupted after a master/backup switchover.

Context

On the network shown in Figure 1, users access Device A and Device B over a switch. A Virtual Router Redundancy Protocol for IPv6 (VRRP6) group is configured on Device A and Device B, with Device A as the master device and Device B as the backup device.

In normal circumstances, Device A forwards both upstream and downstream traffic. If Device A or the link between Device A and the switch fails, a master/backup VRRP6 switchover is triggered and Device B becomes the master device. Then, Device B needs to advertise a network segment route to network-side devices so that downstream traffic is directed from the network side to Device B. However, if Device B has not learned ND entries from user-side devices, the downstream traffic is interrupted. Device B can properly forward downstream traffic only after it learns ND entries from user-side devices.

If ND entries are not synchronized from Device A to Device B and a master/backup switchover occurs, downstream traffic may be interrupted because Device B fails to learn ND entries from users-side devices in time. To resolve this problem, deploy dual-device ND hot backup on Device A and Device B.

Figure 1 Dual-device ND hot backup

Perform the following steps on the devices that back up ND entries from each other:

Procedure

Configure basic VRRP6 group functions.
1. Run system-view
  The system view is displayed.
2. Run interface { interface-name | interface-type interface-number }
  The interface view for the VRRP6 group is displayed.
3. Run vrrp6 vrid virtual-router-id [virtual-ip virtual-address[link-local]]
  The interface view for a VRRP6 group is displayed.
4. Run vrrp6 vrid virtual-router-id virtual-ip virtual-ipv6-address
  A VRRP6 group is created and assigned a virtual IPv6 address.
5. Run vrrp6 vrid virtual-router-id preempt-mode timer delay delay-time
  A preemption delay is set for devices in the VRRP6 group.
  
  You are advised to set the preemption delay to 0 on a backup device to allow it to immediately preempt the master role or set the preemption delay to a non-0 value on the master device so that it can preempt the master role after a specified delay if a master/backup VRRP switchover is performed.
6. Run vrrp6 vrid virtual-router-id priority priority-value
  A priority is configured for a device in the VRRP6 group.
7. Run vrrp6 vrid virtual-router-id timer advertise advertise-interval
  The interval for sending VRRP6 Advertisement packets is configured.
  
  The interval for sending VRRP6 Advertisement packets cannot be less than the time required for a master/backup switchover. Otherwise, VRRP intermittently goes down. You are advised to set the interval for sending VRRP6 Advertisement packets to more than 1 second.
8. Run commit
  The configuration is committed.
9. Run quit
  Exit the interface view.
Configure an RBS.
1. Run remote-backup-service remote-backup-service-name
  An RBS is created, and the RBS view is displayed.
2. Run batch-backup service-type nd now
  The user service configured for the RBS is immediately backed up.
3. Run commit
  The configuration is committed.
4. Run quit
  Exit the RBS view.
Configure an RBP.
1. Run remote-backup-profile profile-name
  An RBP is created, and the RBP view is displayed.
2. Run peer-backup hot
  A backup mode is configured for user information backup between devices.
3. Run vrrp6-id vrid interface {interface-name | interface-type interface-number
  The RBP is bound to the VRRP6 group.
  
  The vrid parameter specifies the ID of a VRRP6 group. The ID must be the same as the VRRP6 group's ID configured using the vrrp6 vrid virtual-router-id [ virtual-ip virtual-address ] command in the interface view.
4. Run backup-id backup-id remote-backup-service service-name
  A backup ID is set for the RBP, and the RBP is associated with the RBS.
  
  The backup-id parameter specifies a backup ID for the RBP. You can use a backup ID and an RBS to determine an RBP. The backup IDs configured for the same RBP must be the same on the master and backup devices and can no longer be configured for other RBPs.
5. Run commit
  The configuration is committed.
6. Run quit
  Exit the RBP view.
Enable the remote backup function for ND.
1. Run remote-backup-profile profile-name
  The RBP view is displayed.
2. Run service-type nd
  The remote backup function for ND is enabled.
3. Run commit
  The configuration is committed.
4. Run quit
  Exit the RBP view.
Bind the RBP to an interface.
1. Run interface interface-type interface-number [.subinterface-number ]
  The interface view for the VRRP6 group is displayed.
2. Run remote-backup-profile profile-name
  The RBP is bound to the interface.
  
  The name of the RBP to be bound to an interface must be the same as the name of the RBP created using the remote-backup-profile command in the system view.
3. Run commit
  The configuration is committed.