08-08-2010 06:21 PM - edited 03-06-2019 12:22 PM
Hi all,
I have a strage spanning-tree case seeking your help, the background is as follow:
Currently we have 3 physical sites, site A (production data centre), site B (DR data centre) and site C (BCP office), those 3 sites has Cisco 6506E, a pair of stacked 3750 and a 3560 switch respectively. The service provider using QinQ tunnel to provide the WAN services to us like the following simple picture:
site A (switch A) -------trunk in my switch and SP using VLAN ID 701-------site B (switch B)-------trunk in my switch and SP using VLAN ID 709 --------site C (switch C)
all these 3 switches are running the same MSTP region and the configuration are the same, same region name, same revision number, and instance (instance 0 for VLAN 1 and VLAN 2-4094 in instance 1), and we have manually configure the switch A being the root bridge for all of the instance.
However, recently, the switch B say it is the root bridge of instance 1, so there are 2 root bridge in the network for instance 1 and switch C also said switch B is the root of instance 1. Switch B is successful to receive BPDU from switch A, and it say switch A is root for instance 0. But from the debug spanning-tree all message, it said the trunk port connecting to switch A (sanity: mrecord missing).
I have searched in Internet but have no luck. Now we don't have spanning-tree issue because the connection is not a loop in our network. But I will feel more comfortable if switch B can get BPDU normally. Would you please help in this case and how can I solve the problem of mrecord missing?
Thank you
Best Regards,
Terry Chow
08-08-2010 06:45 PM
Terry,
How did you assign Switch A as root ?
Could you do a "spanning-tree mst 0 priority 0" and "spanning-tree mst 1 priority 0" on Switch A?
Reset the revision number to a +1 higher than whats in Switch B
Check the Status on both
Please carry out these changes in non-production hours or weekends..
MST can be a real PITA if not handled properly..-:)
08-08-2010 07:26 PM
Hi Tharak,
I am using the command "spanning-tree mst 0-1 priority 24576" to set switch A as the root, and other switches using the default 32768.
Should I also change the revision number in switch B and C also?
Thank you.
08-09-2010 04:38 AM
Yes, you need to set the revision number as same in all the switches in the same region...say 10.
This parameter wont get incremented on changes.
08-09-2010 06:06 PM
Thank you Tharak,
I will schedule a maintenance window to test it.
Thank you.
Best Regards,
Terry Chow
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