Connetcing SpanningTree to FabricPath Domain

[pawel.kwasniewicz]

Hi,

I have a question regarding connection between Spanning Tree and FabricPath domains.

According to the Cisco documentation all fabricpath CE ports where we have STP devices connected should be configured with highest priority (STP Root) from the STP domain perspective.

This can cause a problem in the case when we're connecting existing STP infrastructure with STP root bridges already configured ie. for DC migration proposes.

Are you aware of any recommendation or document from Cisco describing this scenario?

ie.

Kind regards,

Pawel

[Shahzad Arain]

Please refer to following link.

http://www.cisco.com/en/US/docs/switches/datacenter/nexus5000/sw/fabricpath/513_n1_1/fp_n5k_interfaces.html

http://www.cisco.com/en/US/prod/collateral/switches/ps9441/ps9402/white_paper_c11-687554.html

http://www.cisco.com/en/US/docs/switches/datacenter/sw/6_x/nx-os/fabricpath/configuration/guide/fp_interfaces.html

[pawel.kwasniewicz]

Hi,

thanks for the answer

I understand that Cisco recommends to have FP domain as root for STP, but what can be done when we have situation when we can't change the root bridge for STP domain? ( ie. connecting two DC's new-fabricpath and old-stp when changing root bridge in old-stp DC we will cause topology recalculation = downtime, which in my case is not acceptable)

Regards,

Pawel

[Thomas Schmidt]

Hi Pawel,

quite late and not really a solution - more a kind of workaround which worked suitable during our DC network migration a few weeks ago:

We've restricted the connection between old (PVRSTP+) and new (FP) network to one 10GE link. On N5k side we have implemented "bpdu filter" on the interface. With this we were able to connect the network without any STP recalculation.

We were aware of the link fault risk which would have caused severe trouble (depending of current situation of sever migration). Therefore we've tried to shorten this period to the minimum. We were successful to do the migration within 6 weeks (~100 servers / ~200 links) without any issues and finally switched of the old network.

Best regards

Thomas