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

Vlan1(U), Gi1/0/25(U), Gi1/0/26(U), Te1/0/1(U), Te1/0/2(U)

Vlan 2

ccey

Te1/0/1, Te1/0/2

Vlan 3

ccmy

Te1/0/1, Te1/0/2

Vlan 4

me

Te1/0/1, Te1/0/2

Vlan 5

Hermes-Uwrtr1

Te1/0/1, Te1/0/2

Vlan 6

Vlan 9

firewall

Te1/0/1, Te1/0/2

Vlan 10

Vlan 90

VLAN0090

Te1/0/1, Te1/0/2

Vlan 91

Vlan 99

ITC-Office-Inside

Te1/0/1, 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
[MERLIN LOGO]
100 - 135 Innovation Drive
Winnipeg, MB, R3T 6A8
(204) 977-6824 or 1-800-430-6404 (MB only)
athompson@merlin.mb.ca
www.merlin.mb.ca