At the time of writing (29/03/2024) the recommended EXOS (SwitchEngine) version for the X450-g2, X460-g2 and 5420 (as well as other hardware) is EXOS 31.7.2.28-patch1-75.
We recently purchased some new 5420 switches and are upgrading some existing X450-g2 and X460-g2 to the latest recommended software versions. However we have identified an issue that currently at the time of writing an open issue (with Extreme Networks).
https://extreme-networks.my.site.com/ExtrArticleDetail?an=000113491
Symptoms
Following the upgrade to the EXOS 31.7.2.28-patch1-75, it was observed the Out-of-Band (OOB) management port fails, i.e. it stops responding to all connections, is not pingable or usable. A reboot of the switch does not resolve the issue, removing and re-adding the IP address to the OOB (mgmt) interface also does not resolve the issue.
Reverting back to an earlier software version, e.g. EXOS 31.3.1.3-patch1-10 which was present on the new 5420 switches we procured resolves the issue, the OOB management port then appears to work as expected.
Workload (and Resolution)
Currently (at time of writing) there is no formal resolution for the issue, it is an open issue. However the issue points to the OOB mgmt port being susceptible to ARP requests hitting it during the boot-up of the switch, it appears this causes the OOB port to fail.
The current workaround we have is to unplug the OOB management port (or disable the switch port to which it is connected) while the switch is rebooted. So in our case it involved performing the upgrade with the OOB mgmt port unplugged, then plugging it back in once the switch was booted, at that point the OOB management port appears to work without issue.
If the switch needs to be rebooted for any reason, it is required to disable or unplug the OOB mgmt port before rebooting to ensure it does not fail on boot of the switch, then re-enable once the switch is booted.
Further investigations have confirmed that if the port used for Out-of-Band is 100Mbit the issue appears, if the Out-of-Band port of the switch is connected to a 1Gbit port the issue does not appear to be present and a reboot of the switch does not cause the OOB port to fail.