Nexus - Troubleshooting vPC Consistency Issue


Fri, 08/31/2012 - 04:09
Aug 31st, 2012
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This document provides a solution for vPC consistency that occurs between 2 vPC peer devices.

Core Issue

Getting N7K SVI type-2 configuration incompatible message in Nexus 7K

Example: N7K1# show vpc

Legend:                (*) - local vPC is down, forwarding via vPC peer-linkvPC 
domain id                         : 1 
Peer status                      : peer adjacency formed ok     
vPC keep-alive status        : peer is alive                
Configuration consistency
status                               : success Type-2 consistency status : failed 
Type-2 consistency reason:SVI type-2 configuration incompatible
vPC role                             :primary                      
Number of vPCs configured  : 27 
Peer Gateway                     : Disabled


Some configuration mismatches between vpc peers can cause unexpected or wrong forwarding.Therefore some checks are 
performed on the configuration of the vpc  peers to see if those parameters are matching, these parameters can be global or
on a vpc.
The configuration parameters that need to match on both vpc peers are classified as type-1 and type-2.Type-1
mismatches being more severe,trigger some actions from the devices, such as suspending a vpc, not allowing the cluster to form.
With type-2 configuration error, an error will be syslogged, but no action will be taken by the nexus.For complete list of parameters
that must or should be identical between the vPC peers refer
Compatibility Parameters for vPC Interfaces

Note that  Note that Interface vlans must be in the same state (admin up or down) on both vPC peers.

To display the consistency of parameters that must be compatible across the virtual port-channel (vPC) interfaces,
use the show vpc consistency-parameters command.

Sample Output

switch# show vpc consistency-parameters interface po 15 
       Type 1 : vPC will be suspended in case of mismatch
Name                        Type  Local Value            Peer Value             
-------------               ----  ---------------------- -----------------------
STP Mode                    1     Rapid-PVST             Rapid-PVST            
STP Disabled                1     None                   None                  
STP MST Region Name         1     ""                     ""                    
STP MST Region Revision     1     0                      0                     
STP MST Region Instance to  1                                                  
 VLAN Mapping                                                                  
STP Loopguard               1     Disabled               Disabled              
STP Bridge Assurance        1     Enabled                Enabled               
STP Port Type               1     Normal                 Normal                
STP MST Simulate PVST       1     Enabled                Enabled               
Allowed VLANs               -     1-10,15-20,35,45,99    1-10,15-20,35,45,99

Nexus - vPC Recommendations

Configuring vPCs



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