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New Member

Rapid Spanning Tree Problem

Hi all,

I am experiencing an RSTP problem. I have two swtitches connected via wireless link, the port is in trunk mode, the native vlan is vlan 1 the problem is that bpdu's are exchanged for other vlan's but not for vlan 1, when i connect a second backup wireless link it causes the loop, it seems that there are no bpdu exchanges between switches for vlan 1, also in trunk ports i see that BPDU's for vlan 1 are sent by both switches but they do not receive any BPDU's from each other. Any explanation about thiss issue ?

Thanks in advance

  • Other Network Infrastructure Subjects

Re: Rapid Spanning Tree Problem

I would need to know some things to troubleshoot this:

1. Is VLAN 1 the native VLAN of the trunk, on both sides?

2. I presume VLAN 1 is in the allowed VLANs list on both sides of the link?

3. If the native VLAN is not 1, is the native VLAN allowed on the trunk, on both sides?

4. What model of switch is it, and what version of the software?

5. Can you do a show run int for each end of each trunk link?

6. Can you do a show int xxx trunk for each end of each trunk link?

7. Can you do a show spanning-tree vlan 1 on each side of each trunk?

Kevin Dorrell


New Member

Re: Rapid Spanning Tree Problem

1. Yes the VLAN 1 is the native on trunk on both sides.

2. Yes it is allowed on both sides of trunk links.

4.Switches are Cisco 2950 model with IOS version of c2950-i6q4l2-mz.121-22.EA8.bin on both switches

New Member

Re: Rapid Spanning Tree Problem

I forget to add this file.

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