11-12-2011 09:36 PM - edited 03-07-2019 03:21 AM
Hi,
I'm deploying a pair of Nexus 3064 switches in a VPC and they will handle all of the Layer 3 Routing and switching for a small data center. My question is, should I set their spanning tree priority the same if they will be configured as a VPC?
Example:
Primary - 4096
secondary - 4096
Thank you
Solved! Go to Solution.
11-13-2011 12:25 PM
Hi,
Having the same bridge priority is not a requirement to maintain vPC consistency.
Even if you had the highest bridge priority in the secondary, your vPC primary would forward BPDUs in vPC domain.
quoted from "Cisco NX-OS Virtual PortChannel: Fundamental Design Concepts..."
"vPC by default ensures that only the primary switch forwards BPDUs on vPCs. This modification is strictly limited to
vPC member ports. As a result, the BPDUs that may be received by the secondary vPC peer on a vPC port are
forwarded to the primary vPC peer through the peer link for processing.
Note: Non-vPC ports operate like regular spanning-tree ports. The special behavior of the primary vPC member
applies uniquely to ports that are part of a vPC."
{some articles for refe}
http://www.cisco.com/en/US/prod/collateral/switches/ps9441/ps9670/design_guide_c07-625857.pdf
Having the same (highest) priority would also be no problem because in the non-vPC context (i.e. classic spanning tree topology) there would be a tie-breaker (lowest MAC) to elect the root.
Afterall I suppose it's a choice of design.
11-13-2011 12:25 PM
Hi,
Having the same bridge priority is not a requirement to maintain vPC consistency.
Even if you had the highest bridge priority in the secondary, your vPC primary would forward BPDUs in vPC domain.
quoted from "Cisco NX-OS Virtual PortChannel: Fundamental Design Concepts..."
"vPC by default ensures that only the primary switch forwards BPDUs on vPCs. This modification is strictly limited to
vPC member ports. As a result, the BPDUs that may be received by the secondary vPC peer on a vPC port are
forwarded to the primary vPC peer through the peer link for processing.
Note: Non-vPC ports operate like regular spanning-tree ports. The special behavior of the primary vPC member
applies uniquely to ports that are part of a vPC."
{some articles for refe}
http://www.cisco.com/en/US/prod/collateral/switches/ps9441/ps9670/design_guide_c07-625857.pdf
Having the same (highest) priority would also be no problem because in the non-vPC context (i.e. classic spanning tree topology) there would be a tie-breaker (lowest MAC) to elect the root.
Afterall I suppose it's a choice of design.
11-13-2011 07:58 PM
Thank you for the detailed explanation.
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