Руководство По Проектированию для Cisco Cisco Nexus 5010 Switch
Design Guide
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vPC Consistency Checks
Similar to regular PortChannels, virtual PortChannels are subject to consistency checks and compatibility checks.
During a compatibility check, one vPC peer conveys configuration information to the other vPC peer to verify that vPC
member ports can actually form a PortChannel. For example, if two ports that are going to join the channel carry a
different set of VLANs, this is a misconfiguration.
Depending on the severity of the misconfiguration, vPC may either warn the user (Type-2 misconfiguration) or
suspend the PortChannel (Type-1 misconfiguration). In the specific case of a VLAN mismatch, only the VLAN that
differs between the vPC member ports will be suspended on all the vPC PortChannels.
You can verify the consistency between vPC peers by using the command show vpc consistency-parameter:
tc-nexus5k02# show vpc consistency-parameter
Inconsistencies can be global or interface specific:
●
Global inconsistencies: Type-1 global inconsistencies affect all vPC member ports (but do not affect non-vPC
ports)
●
Interface-specific inconsistencies: Type-1 interface-specific inconsistencies affect only the interface itself
Examples of areas where Type-1 inconsistencies may occur include:
●
Multiple Spanning Tree (MST) region definition (VLAN-to-instance mapping)
●
MTU value
●
Spanning-tree global settings (Bridge Assurance, loop guard, and root guard)
●
Configuration changes to the following (these affect only individual vPCs for all VLANs on the vPC):
◦
PortChannel mode
◦
Trunk mode
◦
Spanning-tree interface settings
Note: Mismatched quality-of-service (QoS) definitions were originally Type-1 inconsistencies, but in newer
releases are Type-2 inconsistencies. For the Cisco Nexus 5000 Series, starting from Cisco NX-OS 5.0(2)N1(1) QoS
releases are Type-2 inconsistencies. For the Cisco Nexus 5000 Series, starting from Cisco NX-OS 5.0(2)N1(1) QoS
inconsistencies are categorized as Type 2, and so they do not bring down vPC member ports if the configurations
differ between vPC peers.
The main inconsistencies that you need to be aware of are listed in Table 1. This table also shows which
inconsistencies are global (that is, which bring down all vPCs) and indicates recommended operations to avoid
disruptions.
Table 1.
vPC Consistency Checks
Type-1 Inconsistency
Impact
Recommendation
VLAN to MST Region mapping mismatch
Global
Pre-provision and MAP all VLANs on the MST region
System MTU
Global
Operate change during maintenance window
Rapid-PVST+ Asymmetrically Disabled
Global
Disabling STP is NOT a Best practice
STP global settings (BA, Loop Guard, Root Guard)
Global
Use per-interface STP configurations
STP Mode mismatch
Global
None (Network misconfiguration)
Port-channel mode (active/on)
vPC
Operate change during maintenance window
Port MTU/Link Speed/Duplex mode/Qos
vPC
Operate change during maintenance window
Trunk mode and Native VLAN
vPC
Operate change during maintenance window
STP interface settings
vPC
Operate change during maintenance window
Asymmetric VLANs on the trunk
VLAN on vPC
Acceptable Impact