08-30-2013 02:52 AM - edited 03-07-2019 03:13 PM
Hi All,
I Just setup a cisco 3750 switch with 12.2(55)SE8 image, whenever I connect my laptop or another switch to it takes 20 minutes for the interface to go from orange to green.
any help will be much appriciated.
Many thanks.
08-30-2013 03:29 AM
what's in the log at that time?
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08-30-2013 03:33 AM
Hi Kamran,
What 'spanning-tree' commands are you using on these switchports?
Ensure you have the following commnad enabled globally:
spanning-tree portfast bpduguard default
On all swithports connected to a Pc or server use:
spanning-tree portfast
When you are experiencing the problem, once the above commands have been used, use the following command to gain some insight as to whether it is a spanning-tree issue:
sh spanning-tree summary totals
cheers,
Seb.
08-30-2013 04:17 AM
Hi Seb,
Its the light that stays orange for a while but the link comes up striaght away when i connect, I can ping it as well.
many thanks.
08-30-2013 04:40 AM
An amber light means the switchport is in a blocking state. Whilst this is happening, what is the output for:
sh int status err
09-02-2013 05:49 AM
Hi Seb
Thanks for your help, Issue is sorted with the help of the information you provide.
Just a quick one. what is the difference between these two commands.
spanning-tree portfast bpduguard default
spanning-tree portfast
Many thanks.
09-02-2013 06:28 AM
spanning-tree portfast ...is applied per-interface and is only active when the interface is in non-trunking mode. Essentially it means the port transitions into STP forwarding mode as soon as the link comes up. Without this a port would sit in a listening state for between 30-50 seconds.
spanning-tree portfast bpduguard default ...is enabled globally on the switch. When a switchport with port-fast enabled receives a BPDU it will put the interface in an errdisable state. You will then have to manually 'no shutdown' this interface to bring it back up. Obviously after you have investigated where the BPDU came from!
cheers,
Seb.
09-03-2013 08:10 AM
Hi Seb,
I have applied only spanning-tree portfast default globaly and it works fine but as soon as I apply
spanning-tree portfast bpduguard default it puts the ports connected to voice gateway to err-disabled but the ports connected to IP Telephony Servers are fine.
Here is my stp configuration on the switch:
spanning-tree mode pvst
spanning-tree portfast default
spanning-tree extend system-id
Sorry dont know much about STP
Many thanks.
09-03-2013 08:37 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
For the gateway ports that error disable, and when using portfast and bpduguard global defaults, add to the interface:
spanning-tree portfast disable
spanning-tree bpduguard disable
NB: just disabling bpduguard will avoid the err-disable, but don't recommend having portfast active without bpduguard.
PS:
BTW, you might also consider using rapid-pvst, i.e. the global command:
spanning-tree mode rapid-pvst
09-03-2013 08:54 AM
Hi Joseph,
If I apply the following commands globally:
spanning-tree portfast bpduguard default
spanning-tree portfast default
and then on the interfaces where gatway is connected:
spanning-tree portfast disable
spanning-tree bpduguard disable
after applying these commands would it bring the interfaces straight away because i had issues with interfaces, they were taking 5 minutes to come up.
many thanks.
09-03-2013 09:25 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
There may be a delay on the ports w/o portfast configured (i.e. the gateway ports); more so with regular STP (vs. rapid-STP).
PS:
I also wanted to mention, if you have not already done so, you might want to explicitly select your root bridge. Usually the center of the L2 topology and/or where the gateway for the subnet resides.
09-04-2013 01:48 AM
Thanks Joseph,
I have got another switch configured with following global commands.
spanning-tree mode rapid-pvst
spanning-tree portfast default
spanning-tree portfast bpduguard default
no spanning-tree optimize bpdu transmission
spanning-tree extend system-id
and on in the interfaces I have only got.
spanning-tree portfast disable
Do you think this configuration is ok ?
This switch will be connected to two core switches via uplink and they have configured root bridge on one of the core switches.
Many thanks.
09-04-2013 02:47 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
Do you think this configuration is ok ?
Yes, although you should only need to disable the global portfast and bpduguard settings on interfaces that connect to devices that err-disable the interface. Also, ideally, you want all your STP, on all your devices, running rapid-PVST.
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