09-16-2011 10:13 PM - edited 03-07-2019 02:16 AM
Hi,
can somoen please explain how can i stop STP processs between two switches ?
09-16-2011 10:30 PM
Hi Tarun,
You can stop spanning tree by issuing below command.
no spanning-tree vlan
Note: This is not advisable.
https://supportforums.cisco.com/thread/2046805
Please rate if helpful.
Ameya
09-17-2011 04:33 AM
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The Author of this posting offers the information contained within this posting without consideration and with the reader's understanding that there's no implied or expressed suitability or fitness for any purpose. Information provided is for informational purposes only and should not be construed as rendering professional advice of any kind. Usage of this posting's information is solely at reader's own risk.
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Posting
As Ameya notes, this isn't really advisable; curious why you want to stop STP.
09-17-2011 05:22 AM
Hi,
If you are sure about your network topology, ie. there is no redundant paths which leads to loops then you can disable spanning tree.
++ By default, spanning tree runs on every port. Kindly note that the spanning tree feature cannot be turned off in switches on a per-port basis.
++ you can turn off STP on a per-VLAN basis, or globally on the switch. Extreme care should be taken whenever you disable spanning tree because this creates Layer 2 loops within the network.
++ Use the no spanning-tree vlan
++ Also ensure that all switches and bridges in the VLAN have spanning tree disabled. You cannot disable spanning tree on some switches and bridges in a VLAN and leave it enabled on other switches and bridges in the VLAN. If you do this, you can have unexpected results because switches and bridges with spanning tree enabled have incomplete information in regards to the physical topology of the network.
Please refer the below link for more details
Hope this answers your question.
Cheers
Somu
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09-17-2011 06:17 AM
Thanks everyone.
How about putting the ports in port fast mode.
Say I have as simple as 2 switches with backup link and if I put ports in portfast mode then still STP process will occur?
Sent from Cisco Technical Support iPhone App
09-17-2011 06:22 AM
Hi,
Port-fast is configured only on access ports. It should not be configured on a trunk link where the two switches getting connected.
SW2(config)#int f0/6
SW2(config-if)#
spann portfast
%Warning: portfast should only be enabled on ports connected to a single host. Connecting hubs, concentrators, switches, bridges, etc… to this interface when portfast is enabled, can cause temporary bridging loops.
Use with CAUTION
If you are sure that enabling port-fast will not cause any loops you can use that.
Here’s what happens with the ‘trunk’ option enabled:
SW2(config)#int fa0/6
SW2(config-if)#spann portfast trunk
%Warning: portfast should only be enabled on ports connected to a single host. Connecting hubs, concentrators, switches, bridges, etc… to this interface when portfast is enabled, can cause temporary bridging loops.
Use with CAUTION
SW2#sh spanning-tree int f0/6 portfast
VLAN0001 enabled
VLAN0005 enabled
VLAN0007 enabled
VLAN0008 enabled
VLAN0009 enabled
VLAN0010 enabled
VLAN0022 enabled
VLAN0043 enabled
VLAN0058 enabled
VLAN0067 enabled
VLAN0079 enabled
VLAN0146 enabled
Hope this helps.
Cheers
Somu
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09-17-2011 06:31 AM
Hi Tarun,
It is a wrong notion that portfast stops STP.
Yes it is true that portfast directly takes a switchport in forwarding state but underlying theory is that just the STP states are bypassed.
Now consider there are 3 swithces A,B and C.
Each is connected to one another back to back.
Now even though you configure all uplinks as portfast STP will work.
Reason is that portfast do not stop BPDU transmission.
Now with back to back connectivity in A,B and C we have a Layer 2 loop and thus one port will transition in blocking state.
Only way by which you can ensure STP doesnt work is via no spanning-tree vlan abc cmd.
Please rate the helpful posts.
Ameya
09-17-2011 08:48 AM
Hi,
Yes it is true that portfast directly takes a switchport in forwarding state but underlying theory is that just the STP states are bypassed
And no TCNs are issued when the port goes up or down.
Regards.
Alain.
09-18-2011 05:58 AM
Disclaimer
The Author of this posting offers the information contained within this posting without consideration and with the reader's understanding that there's no implied or expressed suitability or fitness for any purpose. Information provided is for informational purposes only and should not be construed as rendering professional advice of any kind. Usage of this posting's information is solely at reader's own risk.
Liability Disclaimer
In no event shall Author be liable for any damages whatsoever (including, without limitation, damages for loss of use, data or profit) arising out of the use or inability to use the posting's information even if Author has been advised of the possibility of such damage.
Posting
And no TCNs are issued when the port goes up or down.
Unsure that's true if a portfast port is "seeing" BPDUs.
There was another recent posting where Peter Paluch noted change in behavior of portfast ports when they see a BPDU, see: https://supportforums.cisco.com/message/3219909#3219909
Peter didn't address whether portfast behavior change impacts TCN too.
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