Understanding IPv6 Hot Standby

Before deploying IPv6 in the hot standby networking, understand the differences between IPv6 hot standby and IPv4 hot standby.

Internet Protocol Version 6 (IPv6) is a network layer protocol of the new version. It is a set of specifications designed by the Internet Engineering Task Force (IETF). IPv6 addresses are extended to 128 bits in length.

IPv6 can solve the problem of insufficient IP addresses thoroughly. Additionally, with IPv6, the routing entries of routers on the network decrease, improving the forwarding rate of packets.

To improve the reliability of an IPv6 network, two FWs must be deployed to form hot standby.

Different from IPv4, pay attention to the following points when deploying IPv6 hot standby:

By default, the FW is disabled from forwarding IPv6 packets. The global IPv6 function (ipv6) and interface IPv6 function (ipv6 enable) must be enabled.
On an IPv6 network, the heartbeat interface can use IPv4 and IPv6 addresses. As IPv4 heartbeat packets use smaller bandwidth and are more reliable, IPv4 addresses are recommended.
After configuring an IPv6 address for an interface, wait for the IPv6 protocol on the interface to go Up before you create a VRRPv6 group on the interface. This prevents unexpected active/standby switchover.
When configuring a VRRPv6 group, you must configure a link-local address and then a virtual IPv6 address for the group (this IP address cannot be an anycast address). The detailed configuration procedure is as follows:
- Create an VRRPv6 backup group and specify the link-local address and status of the VRRP group.
```
vrrp6 vrid virtual-router-id virtual-ip virtual-ipv6-address link-local { active | standby }
```
- Configure a virtual IPv6 address.
```
vrrp6 vrid virtual-router-id virtual-ip virtual-ipv6-address
```
VRRPv6 groups do not support VRRP packet authentication.
The IPv6 function cannot be configured on the interface that uses the virtual MAC address function (vrrp virtual-mac enable). Similarly, the vrrp virtual-mac enable cannot be used on the interface configured with the IPv6 function.
To configure a VGMP group to control the cost of dynamic routes, run the hrp adjust ospfv3-cost slave-cost command because IPv6 supports only OSPFv3.
When configuring a VGMP group to monitor the IP-link status, you must create an IP-link based on the IPv6 destination address.
When configuring a VGMP group to monitor BFD sessions, you must create a BFD for IPv6 session.
VGMP groups cannot monitor IPv6 dynamic route faults.
Only IPv4, not IPv6, static routes can be automatically backed up.