I suspect this is related to some dumb thing where some vendors return vlans off by one, and we have an ancient workaround for it which may be misbehaving when interacting with vlans from multiple mibs.

Not quite sure, but you can probably work it out by doing a debugging poll of the module collecting these.

Adam.

From: observium observium-bounces@observium.org On Behalf Of Adam Thompson via observium Sent: 27 August 2020 22:08 To: Observium observium@observium.org Cc: Adam Thompson athompson@merlin.mb.ca Subject: [Observium] bogus VLANs reported on switch

We have a Cisco C2960S running 12.2(55)SE3 that Observium insists has a whole bunch of VLANs that don’t actually exist on the switch.

The VLANs (No Graphs) screen, for example, shows:

VLAN

Description

Other Ports

Vlan 1

default

https://observium.merlin.mb.ca/device/device=444/tab=port/port=19129/ Vlan1(U), https://observium.merlin.mb.ca/device/device=444/tab=port/port=19158/ Gi1/0/25(U), https://observium.merlin.mb.ca/device/device=444/tab=port/port=19159/ Gi1/0/26(U), https://observium.merlin.mb.ca/device/device=444/tab=port/port=19160/ Te1/0/1(U), https://observium.merlin.mb.ca/device/device=444/tab=port/port=19161/ Te1/0/2(U)

Vlan 2

ccey

https://observium.merlin.mb.ca/device/device=444/tab=port/port=19160/ Te1/0/1, https://observium.merlin.mb.ca/device/device=444/tab=port/port=19161/ Te1/0/2

Vlan 3

ccmy

https://observium.merlin.mb.ca/device/device=444/tab=port/port=19160/ Te1/0/1, https://observium.merlin.mb.ca/device/device=444/tab=port/port=19161/ Te1/0/2

Vlan 4

me

https://observium.merlin.mb.ca/device/device=444/tab=port/port=19160/ Te1/0/1, https://observium.merlin.mb.ca/device/device=444/tab=port/port=19161/ Te1/0/2

Vlan 5

Hermes-Uwrtr1

https://observium.merlin.mb.ca/device/device=444/tab=port/port=19160/ Te1/0/1, https://observium.merlin.mb.ca/device/device=444/tab=port/port=19161/ Te1/0/2

Vlan 6

Vlan 9

firewall

https://observium.merlin.mb.ca/device/device=444/tab=port/port=19160/ Te1/0/1, https://observium.merlin.mb.ca/device/device=444/tab=port/port=19161/ Te1/0/2

Vlan 10

Vlan 90

VLAN0090

https://observium.merlin.mb.ca/device/device=444/tab=port/port=19160/ Te1/0/1, https://observium.merlin.mb.ca/device/device=444/tab=port/port=19161/ Te1/0/2

Vlan 91

Vlan 99

ITC-Office-Inside

https://observium.merlin.mb.ca/device/device=444/tab=port/port=19160/ Te1/0/1, https://observium.merlin.mb.ca/device/device=444/tab=port/port=19161/ Te1/0/2

…but VIDs 6, 10 and 91 don’t actually exist on this device:

UMTor1#show vlan id 6

VLAN id 6 not found in current VLAN database

UMTor1#show vlan id 10

VLAN id 10 not found in current VLAN database

UMTor1#show vlan id 91

VLAN id 91 not found in current VLAN database

I have manually re-run discovery, successfully.

Every bogus VID strictly follows a valid VID, i.e. 5 is valid, 6 is not. 9 is valid, 10 is not. 90 is valid, 91 is not. And so on.

Anyone else run into this?

Any ideas how to troubleshoot this?

Thanks,

-Adam

Adam Thompson Consultant, Infrastructure Services https://www.merlin.mb.ca/ 100 - 135 Innovation Drive Winnipeg, MB, R3T 6A8 (204) 977-6824 or 1-800-430-6404 (MB only) mailto:athompson@merlin.mb.ca athompson@merlin.mb.ca http://www.merlin.mb.ca/ www.merlin.mb.ca