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New Member

STP Tuning

Hi Guys

i have a scenario were Default STP is running in the switching Enviroment.My Scenrio is as follows

i have a MDF with one Core Sw 4510 .and 10 IDF s with 2 3560 each.Having fiber connection from each switch to the core and uplink between the switch 48th ports in each IDF

i just kicked off configuration and i could see that STP blocks the uplink between one switch edge and core switch uplink and other linkas are "fwd"

how i want them to run is uplinks to Core sw from each edge sw being up and the uplink between the switch to be in " Alt blk"

same for all floor , please advise on the tweak



Everyone's tags (2)
Cisco Employee

STP Tuning


I do not quite understand your topology and the placement of the Fwd/Blk ports. Can you create a quick sketch of your topology (the MDF and a single IDF will probably suffice) to better understand your situation?

Thank you!

Best regards,


New Member

STP Tuning

two Edge switch in IDF , uplinked to each other and one up link each from these switches to the Core switch.

iwhat i want to achive is the link between egde switch to be in block state and only if one up link to core sw breaks

the uplink between switch has to be opened.plz advise

Re: STP Tuning

Hi Alan,

in this situation i would say that to get the trunk between the 3560 in blk state you would need just to force the 4510 to be the root bridge. In your verification steps remember to check multiple vlan if multiple STP instances are in place (MSTP,PVSTP,PVSTP+ etc..)



PS: a pleasant (and short) reading about it

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