Onboarding EXOS Switch - FA Assingment gets rejected

Niko_P — Wed, 14 Oct 2026 12:50:22 GMT

Hi all,

I’ve got some trouble with onboarding EXOS Switches to my network.

I got a VOSS/Fabric Engine as Core with auto-sense enabled on most ports.

The EXOS switch is factory default and connected to one of the auto-sense ports of the VOSS.

The VOSS Switch has a minimal config.

If I connect the EXOS to the VOSS, the switches try to do FA, Onboarding VLAN 4048 I-SID 15999999.

But the FA assignment gets rejected by the VOSS switch.

I get the following messages on VOSS:

5420M-48W-4YE-FabricEngine CP1 - 0x00374583 - 00000000 GlobalRouter FA INFO Fabric Attach Element Discovered on interface 1/32 Element type clientSwitch (8) Id d8:02:c0:37:d8:00:10:00:00:21

5420M-48W-4YE-FabricEngine CP1 - 0x00374592 - 00000000 GlobalRouter FA WARNING Fabric-Attach-ISID assignment 4048:15999999 was rejected on port 1/32 because the I-SID's associated VLAN is private and the private-vlan setting on the port is not set to isolated/promiscuous.

5420M-48W-4YE-FabricEngine CP1 - 0x0037458f - 00000000 GlobalRouter FA INFO Fabric Attach Assignment rejected: interface 1/32 i-sid 15999999 cvid 4048 rejected due to application error (status 9)

No log messages in the EXOS log, but show fabric attach assignment shows it’s rejected.

It is strange that the VOSS logs said that FA is rejected because of private VLAN settings, I can’t change these settings with auto-sense enabled. The private VLAN setting for vlan 4048 are also the default settings.

It get’s even stranger, if I leave it as it is (in rejected state) and wait for some hours or days, the FA assignment will eventually work on and the EXOS get’s an DHCP IP in the onboarding VLAN 4048. (without any changes)

My VOSS switch is an 5420 running 9.3.4.0
My EXOS switch is an 5320 running 33.5.2.118

But I also encountered this with other models and software.

Has anyone else observed this behaviour?

Regards
Niko

topic Onboarding EXOS Switch - FA Assingment gets rejected in ExtremeSwitching (VSP/Fabric Engine)

Onboarding EXOS Switch - FA Assingment gets rejected