vPC Configuration Synchronization

Virtual port channels (vPC) topologies require identical configurations on peer switches. As a result, you must repeat configurations on both peer switches. This process, which can cause errors due to misconfigurations or omissions, can result in additional service disruptions because of mismatched configurations. Configuration synchronization eliminates these problems by allowing you to configure one switch and automatically synchronize the configuration on the peer switch.

In a vPC topology, each Cisco Nexus 7000 Series switch must have some matching parameters. You can use a vPC consistency check to verify that both Cisco Nexus 7000 Series switches have the same configuration (Type 1 or Type 2). If they do not match, depending on whether it is a global (for example, spanning-tree port mode), a port-level (for example, speed, duplex, or channel-group type), or even a port-channel interface, the vPC can go into a suspended state or a VLAN can go into a blocking state on both peer switches. As a result, you must ensure that the configuration from one switch is copied identically to the peer switch.

Configuration synchronization allows you to synchronize the configuration between a pair of switches in a network. Configuration synchronization and vPCs are two independent features and configuration synchronization does not eliminate vPC consistency checks. The checks will continue. If there is a configuration mismatch, the vPC can still go into a suspended state.

In a FEX Active-Active setup:

  • All the Host Interfaces (HIFs) ports are mapped to the internal vPC.

  • The vPC Config-Sync feature listens to the internal vPC creation notification and triggers a merge of the HIF port configuration.

  • All the future HIF configuration are synchronized with the peer switch, if the merge is successful.

  • The status of HIF is marked as "peer out of synchronization" and the configuration of the interface is not synchronized, if the merge fails.

  • We recommend that you disable vpc-config-sync command before starting ASCII configuration. After the ASCII configuration is completed, enable config-sync command for regular operation.


Note

  • vPC peer-link should be configured and up state.

  • You cannot chose which commands are synchronized.

Prerequisites for vPC Configuration Synchronization

  • vPC peer-link should be configured and up state.

Guidelines and Limitations for Configuration Synchronization

  • You cannot chose which commands are synchronized.

Information about vPC Configuration Synchronization

Benefits of vPC Configuration Synchronization

Configuration synchronization benefits are as follows:

  • Provides a mechanism to synchronize configuration from one switch to another switch.

  • Merges configurations when connectivity is established between peers.

  • Provides mutual exclusion for commands.

  • Supports existing session and port profile functionality.

  • Provides minimal user intervention.

  • Minimizes the possibility of user error.

Supported Commands for vPC Configuration Synchronization

The following types of commands are enabled for configuration synchronization:


Note

The show vpc config-sync cli syntax command lists all the commands that are enabled for configuration synchronization. You cannot choose which commands are synchronized. For more information, see the Cisco Nexus 7000 Series NX-OS Interfaces Command Reference.

  • Type-1 configurations:

    • Global configurations

    • vPC member port-channel configurations

  • vPC configurations.


Note

The configurations can be given on either of the vPC peer switches.

How to configure vPC Config Sync

Enabling vPC Configuration Synchronization

Before you begin

  • You must create identical vPC domain IDs on both vPC peer switches.

  • Before you configure this feature for the entire system, ensure that you are in the correct VDC. To change the VDC, use the switchto vdc command.

SUMMARY STEPS

  1. switch# configure terminal
  2. switch(config)# vpc domain domain-id
  3. switch(config-vpc-domain)# config-sync

DETAILED STEPS

  Command or Action Purpose

Step 1

switch# configure terminal

Enters global configuration mode.

Step 2

switch(config)# vpc domain domain-id

Creates a vPC domain on the device, and enters vpc-domain configuration mode for configuration purposes. There is no default; the range is from 1 to 1000.

Step 3

switch(config-vpc-domain)# config-sync

Enables vPC configuration synchronization.

Note

 

This command must be configured on both the primary and secondary switch.

The table below shows the process of configuration synchronization on switch 1 and switch 2:

Primary Switch

Secondary Switch 


switch-1# configure terminal
switch-1(config)# vpc domain 300
switch-1(config-vpc-domain)# config-sync
 

switch-2# configure terminal
switch-2(config)# vpc domain 300
switch-2(config-vpc-domain)# config-sync

Configuration synchronization is enabled on both switches in the same vPC domain. 


switch-1# configure terminal
switch-1(config)# spanning-tree mode mst

The above configuration is applied on the primary switch and is configuration synchronized to the secondary switch.

The configuration is either successfully applied to both switches or will be failed on both. 


switch-1# show running-config
...
spanning-tree mode mst
...


switch-2# show running-config
...
spanning-tree mode mst
...


switch-2# configure terminal
switch-2(config)# spanning-tree port type
switch-2 default

The configuration is applied on the secondary switch and is configuration synchronized to the primary switch.

Note

 

The configuration can be applied to either switch. 


switch-1# show running-config
...
spanning-tree port type network default
...


switch-2# show running-config
...
spanning-tree port type network default
...

Synchronizing Configuration for a Physical Port vPC

Before you begin

Before you configure this feature for the entire system, ensure that you are in the correct VDC. To change the VDC, use the switchto vdc command.

SUMMARY STEPS

  1. switch# configure terminal
  2. switch(config)# interface type slot/port
  3. switch(config-if)# vpc vpc-id [sync {export | import}]
  4. (Optional) switch(config-if)# show running-config interface ethernet slot/port

DETAILED STEPS

  Command or Action Purpose

Step 1

switch# configure terminal

Enters global configuration mode.

Step 2

switch(config)# interface type slot/port

Specifies the vPC physical port, and enters interface configuration mode.

Step 3

switch(config-if)# vpc vpc-id [sync {export | import}]

Moves port channel into a vPC and enters interface vPC configuration mode. The range is from 1 to 4096.

  • sync export enables the primary switch configuration to be exported to the secondary switch.

  • sync import enables the secondary switch configuration to be imported to primary switch.

Step 4

(Optional) switch(config-if)# show running-config interface ethernet slot/port

(Optional)

Displays the running configuration for the physical port.

Asymmetric Mapping

The table below shows the process of enabling configuration synchronization (asymmetric mapping) on the vPC physical port on the primary and the secondary switch:

Primary Switch

Secondary Switch 


switch-1# configure terminal
switch-1(config)# interface eth1/1
switch-1(config-if)# vpc 100

The physical port (ethernet1/1) is added to the vPC 100 domain on the primary switch.

vPC 100 is not configured on the secondary switch. The configuration will not be synchronized until vPC 100 is added to the secondary switch. 


switch-2# configure terminal
switch-2(config)# interface eth2/3
switch-2(config-if)# vpc 100

Following the configuration of vPC 100 to the secondary switch, the physical ports (interface ethernet2/3 on the secondary switch and interface ethernet1/1 on the primary switch) will be configuration synchronized.

Symmetric Mapping

The table below shows the process of enabling configuration synchronization (symmetric mapping) on the vPC physical port on the primary and the secondary switch:

Primary switch

Secondary switch 


switch-1# configure terminal
switch-1(config)# interface eth1/1
switch-1(config-if)# vpc 100 symmetric
 

switch-2# configure terminal
switch-2(config)# interface eth1/1

The physical port (ethernet1/1) is added to the vPC 100 domain on the primary switch. The physical port (ethernet 1/1) is also present on the secondary switch.

The configuration of the physical port on both the primary and secondary switch will be kept in synchronization. 


switch-1# show running-config interface eth1/10

interface ethernet1/1
  switchport
  switchport mode trunk
  vpc 100


switch-2# show running-config interface eth1/10

interface ethernet1/1
  switchport
  switchport mode trunk
  vpc 100

Synchronizing Configuration of vPC Member Port Channel

Before you begin

Before you configure this feature for the entire system, ensure that you are in the correct VDC. To change the VDC, use the switchto vdc command.

SUMMARY STEPS

  1. switch# configure terminal
  2. switch(config)# interface port-channel channel-number
  3. switch(config-if)# switchport
  4. switch(config-if)# vpc vpc-id [sync {export | import}]
  5. (Optional) switch(config-if)# show running-config interface port-channel channel-number

DETAILED STEPS

  Command or Action Purpose

Step 1

switch# configure terminal

Enters global configuration mode.

Step 2

switch(config)# interface port-channel channel-number

Selects the port channel that you want to use as the vPC peer link for this device, and enters interface configuration mode.

Step 3

switch(config-if)# switchport

Configures the interface as a Layer 2 switching port.

Step 4

switch(config-if)# vpc vpc-id [sync {export | import}]

Moves port channel into a vPC and enters interface vPC configuration mode. The range is from 1 to 4096.

  • sync export enables the primary switch configuration to be exported to the secondary switch.

  • sync import enables the secondary switch configuration to be imported to primary switch.

Step 5

(Optional) switch(config-if)# show running-config interface port-channel channel-number

(Optional)

Displays the running configuration for the port channel.

The table below shows the process of enabling configuration synchronization under port channel 10 on the primary and the secondary switch:

Primary Switch

Secondary Switch 


switch-1# configure terminal
switch-1(config)# interface port-channel 10
switch-1(config-if)# switchport
switch-1(config-if)# vpc 10

The configuration under port-channel 10 is configuration synchronized to the secondary switch.

Note

 

The vpc number command can be given first on either the primary or secondary switch. 


switch-2# show running-config interface po10

interface port-channel10
  switchport
  vpc 10

The configuration is applied on the secondary switch and is configuration synchronized to the primary switch.

Note

 

The configuration can be applied to either switch. 


switch-2# configure terminal
switch-2(config)# interface port-channel 10
switch-2(config-if)# switchport mode trunk

The show running-config interface port-channel channel-number command shows that the configuration synchronization for port channel 10 is successful: 


switch-1# show running-config interface 
port-channel 10

interface port-channel10
  switchport
  switchport mode trunk
  vpc 10



switch-2# show running-config interface 
port-channel 10

interface port-channel10
  switchport
  switchport mode trunk
  vpc 10

Verifying vPC Configuration Synchronization

To verify vPC configuration synchronization, perform one of the following tasks:

Command

Purpose

show running-config vpc-config-sync

Displays whether config-sync is available or not.

show vpc config-sync cli syntax

Displays the list of commands that are able to be configuration synchronized.

show vpc config-sync database

Displays the configuration synchronization database.

show vpc config-sync merge status

Displays the merge status of the switch and of each vPC interface.

show vpc config-sync status

Displays the status of the last 10 operations of the vPC configuration synchronization process.

  • Displays merge status (success/failure).

  • Displays the last action done by the vPC configuration synchronization process and the result of that action.

Feature Information for vPC Configuration Synchronization

Table 1. Feature Information for vPC Configuration Synchronization

Feature Name

Releases

Feature Information

vPC Configuration Synchronization

7.2(0)D1(1)

vPC Configuration Synchronization feature synchronizes the configurations of one switch automatically to other similar switches. .