EOS run both VRRP v2 and v3 at same time for migration as per RFC5798

Anonymous — Thu, 07 Jan 2021 17:40:49 GMT

Hi,

This is the same question I have posted in relation to VOSS, but posting here to cover EOS:

In the process of migrating an S-Series core to VSP. The S Series is running VRRP v2, but would like to make use of v3 to take advantage of the following:

Milliseconds failover vs seconds
IPv6 support
Increase v2 limitation of 254 instances on VSP

RFC 5798 states the following, in summary says to migrate you should run both VRRP v2 and v3 at the same time:

“VRRPv3 Support of VRRPv2
As mentioned above, this support is intended for upgrade scenarios and is NOT recommended for permanent deployments.
An implementation MAY implement a configuration flag that tells it to listen for and send both VRRPv2 and VRRPv3 advertisements.
When a virtual router is configured this way and is the Master, it MUST send both types at the configured rate, even if sub-second.
When a virtual router is configured this way and is the Backup, it should time out based on the rate advertised by the Master; in the case of a VRRPv2 Master, this means it must translate the timeout value it receives (in seconds) into centiseconds. Also, a Backup should ignore VRRPv2 advertisements from the current Master if it is also receiving VRRPv3 packets from it. It MAY report when a VRRPv3 Master is *not* sending VRRPv2 packets: that suggests they don't agree on whether they're supporting VRRPv2 routers.”

I know in EXOS VRRP v2 and v3 are enabled by default, so would help support a migration. EOS and VOSS I can’t seem to find the support.

Initially I would add the v2 + v3 configuration on EOS, but fall-back to VOSS if its not supported.

The plan would go something like this:

Stretch the VLAN being migrated between EOS and VOSS
Shutdown VLAN interface on Core 2 of EOS switch
Configure that same L3 VLAN interface in VOSS but as VRRP v3
Shutdown VLAN interface on Core 1 of EOS switch, now routing only on VOSS
Configure the other L3 VLAN interface on other VOSS switch so have full gateway redundancy
Remove stretch VLAN

This allows me to move the L3 from EOS to VOSS with no downtime.

So I have actually done this same process before in a very large network, same hardware EOS → VOSS.

In that migration though I simply reconfigured the EOS cores from v2 to v3 on a live critical network with no service interruption:

Set all the VRRP priorities so core 1 was master
Removed and replaced all the VRRP config on core 2 to be v3
Changed all the VRRP priorities on core 2 to now be master
Removed and replaced all the VRRP config on core 2 to be v3

This incurred no down time but wasn't really following the letter of the RFC, and this time around working on a more critical system I want to get the process interoperable correctly.

Configuring EOS from v2 to v3 didn’t require me to interop the versions, and it worked, but feel it is perhaps not the best way to do it.

So question is: how do I enable both VRRP v2 and v3 at the same time for each VLAN interface?

Many thanks in advance

topic EOS run both VRRP v2 and v3 at same time for migration as per RFC5798 in ExtremeSwitching (EOS)

EOS run both VRRP v2 and v3 at same time for migration as per RFC5798