# Both switches thinks they are root
**URL:** https://forum.networklessons.com/t/both-switches-thinks-they-are-root/667
**Category:** Spanning Tree
**Created:** [May 9, 2016, 1:17pm UTC](https://forum.networklessons.com/t/both-switches-thinks-they-are-root/667 "2016-05-09T13:17:11Z")
**Posts on this page:** 5
**Page:** 1
### Author:  [@lars](https://forum.networklessons.com/u/lars)
#### Post date: [May 9, 2016, 1:17pm UTC](https://forum.networklessons.com/t/both-switches-thinks-they-are-root/667/1 "2016-05-09T13:17:11Z")
Hi
I have 2 S3048-ON configured with VLT (virtual link trunk), and a Dell 5548 connected to one of the S3048-ON (tried both one and two cables).
All switches are configured with RSTP, and have configured priorities.
But both S3048-ON and Dell 5548 thinks they’re root.
I can’t seem to trigger Dell 5548 to “surrender” and **not** be root bridge.
Haven’t seen this behavior before. Any insights ?
Attached some screenshots.
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### Author:  [@ReneMolenaar](https://forum.networklessons.com/u/ReneMolenaar)
#### Post date: [May 9, 2016, 2:00pm UTC](https://forum.networklessons.com/t/both-switches-thinks-they-are-root/667/2 "2016-05-09T14:00:55Z")
Hi Lars Erik,
That is surprising 🙂 Are you able to verify if both switches do receive BPDUs from each other? That’s the first thing I would check.
I’m not too familiar with the Dell switches but do they perhaps have any filtering enabled by default? Something similar like Cisco’s STP root guard?
Rene
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### Author:  [@lars](https://forum.networklessons.com/u/lars)
#### Post date: [May 23, 2016, 3:48pm UTC](https://forum.networklessons.com/t/both-switches-thinks-they-are-root/667/3 "2016-05-23T15:48:42Z")
Hi Rene
It seems that BPDUs aren’t received at all by the 5548 switch, on the S3048-ONs I see both sent/received (I guess this is between the 2 S3048-ONs this is happening). There’s no guarding of any kind enabled (see screenshot) on 5548. Tried changing BPDU global setting on 5548 to flooding instead of filtering but with no results.
I’ll try changing cables and if that’s not working I’ll try to find another switch to test with (which is not 5548).
BTW: If there’s no normal traffic from attached devices/servers and it’s only switches that is interconnected. Could this tricker no received BPDUs on 5548 ? (or would it always adapt no matter if any traffic occur?)
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### Author:  [@lars](https://forum.networklessons.com/u/lars)
#### Post date: [May 25, 2016, 2:17pm UTC](https://forum.networklessons.com/t/both-switches-thinks-they-are-root/667/4 "2016-05-25T14:17:52Z")
The 5548 switch needed to be configured with LAG/LACP and connect through this to S3048-ONs for RSTP to work as expected. Once this is configured all seems fine, attached screenshot!
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### Author:  [@ReneMolenaar](https://forum.networklessons.com/u/ReneMolenaar)
#### Post date: [May 25, 2016, 8:34pm UTC](https://forum.networklessons.com/t/both-switches-thinks-they-are-root/667/5 "2016-05-25T20:34:34Z")
Hi Lars Erik,
Good to hear you figured it out!
Rene