Migration from VRRP Version 2 to VRRP Version 3

To support smooth migration from VRRP version 2 with IPv4 capability to VRRP version 3 with IPv4 & IPv6 capability, VRRP provides an intermediate version v2-v3. VRRP version v2-v3 is an intermediate version used only during the transition phase from v2 to v3. This version is not a permanent solution or version. Below is the use case scenario of the version v2-v3.

Assume that there are two routers (R1 -> Master and R2 -> Backup) operating in VRRP version v2 mode. To migrate to version v3, the below steps are to be followed.
  1. The default version of VRRP is v2.
  2. Bring up R1 and R2 in release ISS2 with release ISS1’s configurations.
  3. At R2, change the version as v2-v3.
    1. This makes R2 to accept both V2 as well V3 packets from R1.
    2. Since R1 is configured with only v2, it will not transmit V3 packets.
      1. V2 packets carry Authentication fields if authentication is set.
      2. V3 packets DO NOT have authentication as it has been removed in V3 RFC.
    3. V2 packets carry Authentication fields if authentication is set.
    4. V3 packets DO NOT have authentication as it has been removed in V3 RFC.
    In v2-v3 mode, no additional configuration should be done. After topology is settled, at R2, change the version as v3.
    1. his makes R2 to accept only V3 packets from R1.
    2. V2 packets from R1 are discarded and captured as VERSION_ERROR
    At R1, change the version as v3.
    1. This makes R1 to send only V3 packets to R2.

In v2-v3 mode, configurations are saved and restored through V3 MIB. So, authentication MIB objects are not restored in this mode. It is recommended to remove authentication capability before initiating the migration from v2 to v3 through v2-v3 because authentication fields are not filled in V3 packets and not supported by version v3.

Parent topic: VRRP Version 3