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Restricting BPDU Flooding only to VLAN

I am using one Cisco SG300. I am trying to simulate two unmanaged switches in the cisco managed switch using VLANs.

Port 3 - VLAN 2 - Access
Port 4 - VLAN 2 - Access
Port 5 - VLAN 3 - Access
Global STP - Disabled

I am trying to test STP of another device. For this, I enabled 'BPDU Flooding' in SG300.

When I connect 2 ethernet ports of my device to port 3 and port 4 of SG300, my device detects the loop.
When I connect 2 ethernet ports of my device to port 4 and port 5 of SG300, my device still detects the loop. I dont want this to happen. I want to configure SG300 such that BPDU flooding happens only within VLAN. I mean, the BPDU traveling in VLAN 2 should not be seen in VLAN 3 and vice versa.

Can someone please tell what configuration I can do, to make this happen.

Thanks in advance.

uv.

2 REPLIES 2
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VIP Rising star

Re: Restricting BPDU Flooding only to VLAN

BPDU's are NOT sent per VLAN!

so your question "the BPDU traveling in VLAN 2 should not be seen in VLAN 3 and vice versa" is not possible.

but

- you can totally disable bpdu's on port-5 ? read this post:

You always should allow STP to run on a switch to prevent loops. However, in special cases when you need to prevent BPDUs from being sent or processed on one or more switch ports, you can use BPDU filtering to effectively disable STP on those ports.you would use bpdufilter when you want a switch plugged into your network but you don't want it participating in spanning tree.

- or you can want to convert from (R)STP to MST?

  and use separate MST instance for each vlan so each performs its own loop-detection.

 

 

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VIP Mentor

Re: Restricting BPDU Flooding only to VLAN

Hello

 

 


@active.hub2 wrote:

I am using one Cisco SG300. I am trying to simulate two unmanaged switches in the cisco managed switch using VLANs.

Port 3 - VLAN 2 - Access
Port 4 - VLAN 2 - Access
Port 5 - VLAN 3 - Access
Global STP - Disabled

I am trying to test STP of another device. For this, I enabled 'BPDU Flooding' in SG300.

When I connect 2 ethernet ports of my device to port 3 and port 4 of SG300, my device detects the loop.
When I connect 2 ethernet ports of my device to port 4 and port 5 of SG300, my device still detects the loop. I dont want this to happen. I want to configure SG300 such that BPDU flooding happens only within VLAN. I mean, the BPDU traveling in VLAN 2 should not be seen in VLAN 3 and vice versa.

 


The loop is occuring because youve have disabled spanning-tree, enable it then communication should only be allowed between the devices in the same vlan



kind regards
Paul

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