some VLANS lost by trunking from Cisco WS-C3850-12S to Meraki MS120-48LP

[redsector]

Hello, I have got a strange issue with trunk-ports from Cisco classic WS-C3850-12S to Meraki MS120-48LP.

Some VLANs don´t get trough the trunk line. The MS-switches are on Firmware MS14.33 and the Cisco Classic switches are on the newest recommended software version.

The trunk ports are not restricted in any way (all VLANs allowed). VLAN 3 is not possible to get trough, VLAN1,2,5,8 are going trough.

I tried it with port aggregation/etherchannel but also without. Spanning-tree works good. Standard VLAN is VLAN1.

devices in VLAN3  can´t see each other on the other side but each device can see devices in this VLAN on the own switch. Other VLANs are working well, and all devices can see each other independent on which switches.

Is that an bug? Or am I stupid?

[KarstenI]

Anything in the log of the Catalyst? And what is the output of "show spanning-tree vlan 3"? Is the port that connects to the MS forwarding for VLAN3?

[redsector]

the logs are clean

[redsector]

thank you.

show spanning-tree vlan 3:

Po6 Desg FWD 10000 128.2382 P2p

interface Port-channel6
description Uplink to Meraki-Switch
switchport mode trunk
spanning-tree guard loop
end

[CameronS]

Try putting the trunk into native 3 allowed all or even access 3 to see if VLAN 3 gets through at all?

[redsector]

o.k. I will try. but this could last a while. I will keep you informed.

Thank you

[PhilipDAth]

Any chance you have a spanning tree pruning algorithm enabled, and it has pruned VLAN3?

http://etutorials.org/Networking/Lan+switching+fundamentals/Chapter+4.+Layer+2+Fundamentals/VLAN+Pru...