Wired Intelligent Edge

Hi all,

We are running 3 sites with HP Aruba switches. MSTP is enabled (no config nor setup just out of the box).

We are running 12 VLANs across the network. All VLANs are tagged across the links between switches.

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Currently:

Site A  connects to Site B with fibre

Site B connects to Site C with a Wireless Link 

Proposed Change:

Site A  connects to Site B with fibre

Site B connects to Site C with a Wireless Link 

Site B connects to Site C with a second wireless link

Site C to connect to Site A with a wireless link

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Currently at Site B a HP Stack is in the main control room and has a single fibre connection to each of the 6 switches in the factory.

We would like to change this so that the switches are in a ring e.g:

Switch 1 has a connection to switch 6 & switch 2

Switch 2 has a connection to switch 1 & switch 3

Switch 3 has a connection to switch 2 & switch 4

Switch 4 has a connection to switch 3 & switch 5

Switch 5 has a connection to switch 4 & switch 6

Switch 6 has a connection to switch 5 & switch 1

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When we connected the redundant wireless links, spanning tree did not shut down one of the links. This caused me concern that it needs configuration out of the box.

I have provided a visio of our current setup in the attachments.

Could anyone let me know what I am doing wrong please? What do I need to do to make sure that when we change the switches into a "loop" MSTP shuts down one of the links?

Many thanks. Please let me know if this wording does not make sense.

Greetings!

We need a bit more information to get to the bottom of what's going on here.  Could you provide the output of 'show spanning-tree' from each of the switches in the 'looped' state so we can figure out why ports aren't being shut down?  Configurations of the switches in question would also be helpful (you can send these by PM if you'd rather not do so publicly).

Hi Matthew,

As soon as I noticed the ports had not shut-down automatically I manually disabled the loop (circa 10mins after it was plugged in). We had not noticed a spike in traffic but not much was on the network at the time.

I need to double check that all VLANs are added on all switches, would this make a difference?

Thanks,

Phil

Attachment(s)

Site 1 main_switch_spanning.txt   46 KB 1 version

Site 3 main_switch_spanning.txt   18 KB 1 version

Site 2 main_switch_spanning.txt   44 KB 1 version

If this is an out of the box configuration, has Spanning Tree been enabled? The default configuration has MSTP basically operating in RSTP mode, but if I recall correctly Spanning Tree still needs to be globally enabled first.

Hi Charlie,

This is out of the box. MSTP shows as being enabled, but they all seem to have different Root bridge? This would suggest each site has formed it's own perhaps?

It is entirely possible that this is the case.  You mentioned that the inter-site connections (with the exception of the fiber link between A and B) are wireless; have you checked to see if BPDUs are being passed across those links between all three sites?  If they're being blocked, it's likely that each site is simply creating its own local spanning tree with an independent root bridge, which might explain what you're seeing.

Hi All,

I watched some cisco videos last night to try and understand more. It was my impression that the instances all needed the same name. The names on mine all seem to be different, I'm a little confused. Please see details below:

Hi guys, 

Sorry for slow response, I thought I'd posted but it's not been uploaded. I did some research on the cisco variant of MSTP and wondered if my MSTP Config names matched, they do not. I ran "show spanning-tree mst-config" on each switch.
Please see below:

Hi all,

I'm going to triple check all VLANs are enabled on all switches and then re-name the MSTP instances using:

(ArubaS3500) (config) #mstp
(ArubaS3500) (Global MSTP) #region-name MSTP_REGION_A

Is this correct or do I need to do anymore?

Source of info:

http://community.arubanetworks.com/t5/Wired-Networks/Global-MSTP-Configuration-on-MAS/ta-p/234046

Has anyone got any thoughts or advice?

Thanks,

Phil