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STP Design Problem

Can I run different stp in the whole switched network? e.g. run pvst in access layer and rapid pvst in distribution layer

And do I need to turn on backbone fast and uplink fast feature in distribution layer switch if I run rstp in that switch?

Thanks for any help

1 ACCEPTED SOLUTION

Accepted Solutions
VIP Purple

Re: STP Design Problem

Hello Yong,

although RSTP is backwards compatible with (802.1D) STP, when you have a switch in the spanning tree topology that runs (802.1D) STP, all switches will revert to STP. So, in your situation, it would not be possible to run RSTP in the distribution layer, and STP in the access layer.

With regard to RSTP and Backbone/UplinkFast: both are natively used by RSTP, that is, RSTP as an enhancement to STP has incorporated both BackboneFast and UplinkFast into its normal operation. There is no need to turn these features on when you run RSTP, since RSTP is already using them anyway...

Does that make sense ?

Have a look at this document as well:

Understanding Rapid Spanning Tree Protocol (802.1w)

http://www.cisco.com/warp/public/473/146.html#topic1

HTH,

GP

2 REPLIES
VIP Purple

Re: STP Design Problem

Hello Yong,

although RSTP is backwards compatible with (802.1D) STP, when you have a switch in the spanning tree topology that runs (802.1D) STP, all switches will revert to STP. So, in your situation, it would not be possible to run RSTP in the distribution layer, and STP in the access layer.

With regard to RSTP and Backbone/UplinkFast: both are natively used by RSTP, that is, RSTP as an enhancement to STP has incorporated both BackboneFast and UplinkFast into its normal operation. There is no need to turn these features on when you run RSTP, since RSTP is already using them anyway...

Does that make sense ?

Have a look at this document as well:

Understanding Rapid Spanning Tree Protocol (802.1w)

http://www.cisco.com/warp/public/473/146.html#topic1

HTH,

GP

New Member

Re: STP Design Problem

RSTP-capable switches are fully interoperable with 802.1D switches. They simply fall back to 802.1D on a per-port basis when connected to older switches. 802.1D switches ignore 802.1w BPDUs because of their type value. Because of this interoperability, 802.1W capable switches require no special configuration -- 802.1W is active whenever 802.1D is.

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