Using dedicated trunks for VLANs

[Jonathan Scruggs]

So here's the deal. I have a few SG300 switches already setup with several VLANs. I'm using them for regular network traffic as well as some specialized AV network traffic. I have multicast video on one VLAN and I'm planning on setting up a Dante audio network on its own VLAN. For the Dante to work properly it really can't have any other traffic on the lines. We're talking sub-millisecond latency that has little to no tolerance to wait on QOS to decide what to do with the packets.

With that being said, I did some experiments by tagging a certain trunk port with just one VLAN while the other trunk port carried all the other VLANs.

Example, switch 1 and 2 are connected via two separate trunk ports. Trunk 1 has VLAN 1, 10, 30 while trunk 2 only has VLAN 20 on it.

For some reason this didn't work. I lost all communication between the two switches when I configured the second trunk. What I'm I missing?

[Dennis Mink]

what you are trying to do, should work, prune all but one vlan for the Dante and allow all other vlans across the second physical trunk.

can you send us the config for both ends.

cheers

[Jonathan Scruggs]

I just tried reconfiguring as I discribed with the same results. No go.

For whatever reason when I try to backup the config file via HTTPS to post here it won't save to my computer. I tried serveal computers and browsers. The GUI acts like it saved but when you go to open the file, it's not there. Any thoughts there? 

As far as the second trunk goes, I set the VLANs to 1PU, 20T.

It's probably worth noting the main trunk is running through a LAG. I have physical 2 connections in it. For the test I pulled one of those ports from the lag on each switch.

Hopefully that make sense. 

[Dennis Mink]

can you post the config.  thanks

[Jonathan Scruggs]

Topology is as follows:

Switch 1 LAG 1 connected to switch 3 LAG 1.

Switch 1 LAG 2 connected to switch 2 LAG 1.

Switch 1 GE24 trunk connected to switch 2 GE24 trunk.

This was a test to try and isolate VLAN 10 on it's own trunk between switches 1 and 2 while all other VLANs remain on the other trunk.

I figured out if I turned off STP on all our switches with the current configuration it worked but the network was painstakingly slow. As soon as I disconnected GE 24 on switch 1 the network resumed to normal speeds.

Edit: I forgot to untag VLAN 10 from switch 2 LAG 1. It seems to be working as expected now. Should I keep STP turned off with the current configuration?

[Dennis Mink · Accepted solution]

The problem is most likely cause by the native vlan statements on your trunks:

get rid of them.  just only use trunk definitions such as below.

Is there a requirement to use native vlan?

 switchport trunk allowed vlan 10