Cisco Nexus 5000 Series - Graceful Consistency Check

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Cisco Nexus 5000 Series NX-OS Interfaces Operations Guide, Release 5.0(3)N2(1)
Chapter 1 Virtual Port Channel Operations
vPC Consistency Checks
000
Local suspended VLANs - - -
Use the show vpc consistency-parameters interface port-channel number command to display the
interface-level consistency parameters.
This example shows how to display the interface-level consistency parameters:
n5k-1# show vpc consistency-parameters interface port-channel 200
Legend:
Type 1 : vPC will be suspended in case of mismatch
Name Type Local Value Peer Value
------------- ---- ---------------------- -----------------------
STP Port Type 1 Default Default
STP Port Guard 1 None None
STP MST Simulate PVST 1 Default Default
lag-id 1 [(7f9b, [(7f9b,
0-23-4-ee-be-64, 80c8, 0-23-4-ee-be-64, 80c8,
0, 0), (8000, 0, 0), (8000,
0-1e-13-15-7-40, 1, 0, 0-1e-13-15-7-40, 1, 0,
0)] 0)]
mode 1 active active
Speed 1 10 Gb/s 10 Gb/s
Duplex 1 full full
Port Mode 1 trunk trunk
Native Vlan 1 1 1
Shut Lan 1 No No
Allowed VLANs - 1-999,1001-3967,4048-4 1-3967,4048-4093
093
The Cisco Nexus 5000 Series switch conducts vPC consistency checks when it attempts to bring up a
vPC or when you make a configuration change.
In the interface consistency parameters shown in the above output, all configurations except the Allowed
VLANs are considered as Type 1 consistency check parameters. The Allowed VLAN (under the trunk
interface) is considered as a Type 2 consistency check parameter. If the Allowed VLAN ranges are
different on both VLANs that means that only common VLANs are active and trunked for the vPC while
the remaining VLANs are suspended for this port channel.
Graceful Consistency Check
Beginning with Cisco NX-OS Release 5.0(2)N2(1) and later releases, when a Type 1 mismatch occurs,
by default, the primary vPC links are not suspended. Instead, the vPC remains up on the primary switch
and the Cisco Nexus 5000 Series switch performs Type 1 configurations without completely disrupting
the traffic flow. The secondary switch brings down its vPC until the inconsistency is cleared.
However, in Cisco NX-OS Release 5.0(2)N2(1) and earlier releases, this feature is not enabled for
dual-homed FEX ports. When Type-1 mismatches occur in this topology, the VLANs are suspended on
both switches. The traffic is disrupted on these ports for the duration of the inconsistency.
To minimize disruption, we recommend that you use the configuration synchronization feature for
making configuration changes on these ports.
To enable a graceful consistency check, use the graceful consistency-check command. Use the no form
of this command to disable the feature. The graceful consistency check feature is enabled by default.
This example shows how to enable a graceful consistency check:
switch(config)# vpc domain 10