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New Member

vPC peer-switch is enabled (non-operational)

We are wondering about a vPC peer-switch setup whis states to be non-operational!

We are running a Cisco Nexus 7010 vPC pair against a Cisco 6500 VSS setup.

The VSS system is the root of the MST (STP).

We have enabled vPC peer-switch feature on the N7ks.

The two N7ks show the following STP states:

nex7010-1# sh spanning-tree summary Switch is in mst mode (IEEE Standard) Root bridge for: none

Port Type Default                        is disable

Edge Port [PortFast] BPDU Guard Default  is enabled Edge Port [PortFast] BPDU Filter Default is disabled

Bridge Assurance                         is enabled

Loopguard Default                        is disabled

Pathcost method used                     is long

PVST Simulation                          is enabled

vPC peer-switch                          is enabled (non-operational)

STP-Lite                                 is enabled

Name                   Blocking Listening Learning Forwarding STP Active

---------------------- -------- --------- -------- ---------- ----------

MST0000                      0         0        0          2          2

MST0001                      0         0        0          2          2

---------------------- -------- --------- -------- ---------- ----------

2 msts                       0         0        0          4          4

nex7010-2# sh spanning-tree summary Switch is in mst mode (IEEE Standard) Root bridge for: none

Port Type Default                        is disable

Edge Port [PortFast] BPDU Guard Default  is enabled Edge Port [PortFast] BPDU Filter Default is disabled

Bridge Assurance                         is enabled

Loopguard Default                        is disabled

Pathcost method used                     is long

PVST Simulation                          is enabled

vPC peer-switch                          is enabled (non-operational)

STP-Lite                                 is enabled

Name                   Blocking Listening Learning Forwarding STP Active

---------------------- -------- --------- -------- ---------- ----------

MST0000                      0         0        0          2          2

MST0001                      0         0        0          2          2

---------------------- -------- --------- -------- ---------- ----------

2 msts                       0         0        0          4          4

What could be the reason for that vPC peer-switch feature to be enabled but (non-operational)?!

Thank you for any hint!

  • LAN Switching and Routing
Everyone's tags (4)
1 ACCEPTED SOLUTION

Accepted Solutions
New Member

vPC peer-switch is enabled (non-operational)

Hi Stephan,

Allow me to clarify myself,  vPC peer-switch has been introduced into the N7k to improve the convergence time during vPC primary peer device failure/recovery. Without the vPC peer-switch feature, vPC primary peer device failure and recovery usually created around 3 seconds of traffic disruption (for south to north traffic). With vPC peer-switch, traffic disruption is lowered to sub-second value because peer device down an up events do not generate any RSTP Sync behavior (from a STP standpoint, there is no change in L2 topology, there is no new RSTP Root election).

Now to comeback on your topology, as the N7k's are not the primary root bridge STP convergence will not be improved by vPC peer-switch as their is no change in the L2 topology when one of the vPC peer devices fails, the Cat6k VSS will remain the root bridge.

Non-operational means that only the vpc primary will be sending and processing STP BPDU and no virtual System ID is used to appear as a single switch.

I hope this answers your questions

Kristof

3 REPLIES
New Member

vPC peer-switch is enabled (non-operational)

Hi,

When configuring peer-switch the N7k it will  appear as a single STP root in the Layer 2 topology, but since your VSS is the root bridge it states non-operational as peer-switch is only operational on a root bridge.

Please note that the non-operational can also appear when the spanning-tree  prioirty for vlans are not the same on both

sides. If they don't match, it would not become operational.

Kristof

New Member

vPC peer-switch is enabled (non-operational)

Hi Kristof,

thanks for your reply - that's a very usefull hint!

But this implies that the peer-switch feature could never be used, if there is more than one vPC pair in any kind of STP setup (or could only be used on one (the STP-Root-Owner) vPC pair), or do I miss something?

Do you know what (non-operational) means in that case? Does it just mean it works in the same manner as if it wouldn't have been configured, or could it cause any other unpredictable behaviors?

Thank you in advance!

Greetings, _Stephan

New Member

vPC peer-switch is enabled (non-operational)

Hi Stephan,

Allow me to clarify myself,  vPC peer-switch has been introduced into the N7k to improve the convergence time during vPC primary peer device failure/recovery. Without the vPC peer-switch feature, vPC primary peer device failure and recovery usually created around 3 seconds of traffic disruption (for south to north traffic). With vPC peer-switch, traffic disruption is lowered to sub-second value because peer device down an up events do not generate any RSTP Sync behavior (from a STP standpoint, there is no change in L2 topology, there is no new RSTP Root election).

Now to comeback on your topology, as the N7k's are not the primary root bridge STP convergence will not be improved by vPC peer-switch as their is no change in the L2 topology when one of the vPC peer devices fails, the Cat6k VSS will remain the root bridge.

Non-operational means that only the vpc primary will be sending and processing STP BPDU and no virtual System ID is used to appear as a single switch.

I hope this answers your questions

Kristof

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