Describes information needed to be taken into consideration when upgrading VRRP enabled systems - DBHA & MSHA
Customers upgrading X-Series VRRP-enabled systems (Dual-Box High Availability - DBHA or Multi-System High Availability - MSHA) should check if there are any differences in VRRP implementation.
Upgrade considerations from XOS 8.x to 9.5+ are discussed in the Knowledge Base article titled "Remote-box configuration between systems running XOS 8.x and 9.5".
When upgrading VRRP-enabled X-Series systems from XOS prior to XOS versions 9.5.5 SP5, 9.5.6, 9.6.1 to a version equal or higher, Crossbeam recommends that you either upgrade both chassis at the same time or temporarily disable VRRP between chassis for the period of the upgrade.
The XOS versions listed above contain a software fix (30527) documented in the Release Notes:
ID 30527 - Corrected an issue in which alarms indicating a temporary loss of connectivity on remote-box paths could occur in networks with high latencies.
The change modifies the frequency of the remote box timer. Running XOS versions with a different frequency could potentially cause VRRP instabilities.
VRRP might be temporarily disabled on a particular system, leaving one from each VRRP group enabled. Let's call it system OldX. This OldX system will process the traffic. After the upgrade has been completed, VRRP might be enabled on the other system(s) and disabled on the OldX. After traffic has failed over to the other system, this OldX system might be upgraded and then VRRP re-enabled with the previous settings.
The following example is based on a configuration with a single VRRP fail-over group: