Spanning-tree port type for the L2 connectivity between VDCs

[Thiyagarajan K]

Hello All,

I'm working on a design issue and would like know the Cisco best practice to configure the spanning tree port type for the L2 connectivity between VDCs?

In a scenario VDC running on Switch A to VDC running on Switch B and both switch A and switch B are VPC peers.

Shall I configure it as "spanning-tree port type network"

Or

Do we need to use this command only for the connectivity between N7Ks to N5Ks?

switch(config)# interface ethernet 1/4

switch(config-if)# spanning-tree port type network

Regards,

Thiyagu

[Reza Sharifi]

Hi,

spanning-tree port type network should be used only for vPC between switches.

For VDC (switch to switch) you should use spanning-tree port type normal

HTH

[Thiyagarajan K]

Thanks Reza. just to confirm again on my understanding.

1- If there is VPC between N7K and N5K then we have to configure the switch ports as "spanning-tree port type network"

what would be the suggested switch port types for the following scenarios:

1- if there is a connectivity from N7K (VDC) to a downstream 5K switch

2- If there is a connectivity from N7K ( admin VDC) to anonther VDC ( VDC id 2) in the same Nexus 7K switch?

Thanks a lot in advance for your help.

It would be great help if you could also share any document on this?

Regards,

Thiyagu

[Reza Sharifi]

Hi,

spanning-tree port type network should be configured on vPC peer-link.  See page 53  in this document for an example.

http://www.cisco.com/c/dam/en/us/td/docs/switches/datacenter/sw/design/vpc_design/vpc_best_practices_design_guide.pdf

For all the other scenarios, it should be normal. see page 65

HTH

[Thiyagarajan K]

Thanks a lot Reza. The difference with the spanning-tree port type network and spanning-tree port type normal is the bridge assurance feature.

Since the BA feature is disabled on spanning-tree port type normal, Do we need to enable loop guard to prevent any STP loops in the event of any BPDU drops from the neighbor switches?

Regards,

Thiyagu