Issue with PVST and RSTP in 6500 switch running 122-18.SXF17

Unanswered Question
Jul 17th, 2010
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Hi,


I am having RSTP running in my LAN now we have connected another 6500 switch as client running PVST..


We had som problem in LAN and could not trace the issue, not sure if it was due to compatibility issue between RSTP and PVST..


I wanted to know if these two protocol are compatible with each other or not, if not then What all possible problem we can see due to this STP conflict..


Regards

amar

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Mohamed Sobair Sun, 07/18/2010 - 01:09
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Hi,


RSTP is backward compatible with Cisco PVST. if two bridges connected together , one is running RSTP and the other is RSTP, the RSTP bridge fall to PVST. so they are compatible.



what exactly the problem you are facing?



HTH

Mohamed

Ganesh Hariharan Sun, 07/18/2010 - 02:27
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Hi,


I am having RSTP running in my LAN now we have connected another 6500 switch as client running PVST..


We had som problem in LAN and could not trace the issue, not sure if it was due to compatibility issue between RSTP and PVST..


I wanted to know if these two protocol are compatible with each other or not, if not then What all possible problem we can see due to this STP conflict..


Regards

amar

Hi Amar,


STP process would not fail through any combination because RSTP is backwards compatible with PVST.They will work fine together but you need to be aware that any vlan that exists on old switch and  6500 switches will revert to standard 802.1d timers.


Hope to help !!


Ganesh.H


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amardram123 Sun, 07/18/2010 - 07:50
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Hi,


Both are connected through L2tp trunk and vlan sync is working...


I see both the switches are root for all VLANS.. though the root priorty is different..


Regards

amar

Mohamed Sobair Mon, 07/19/2010 - 12:36
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Looks like there is a problem with your L2TP, if bothe switches see themselves as the root for all vlans , it means STP is not tunneled or not syn between both bridges .( No BPDUs are exchanged ).


check if your L2TP config also allows STP to be tunneled.



HTH

Mohamed

amardram123 Fri, 08/13/2010 - 09:45
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Hi,


BPDU filter was getting enabled every time i was enabling L2TP, I disabled it and STP is working fine.


Thanks for help


Amar

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