You can have only two devices as vPC peers; each device can serve as a vPC peer to only one other vPC peer. The vPC peer devices can also have non-vPC links to other devices.

See the following figure for invalid vPC peer configurations.

Figure 4. vPC Peer Configurations That Are Not Allowed

To make a valid configuration, you first configure a port channel on each device and then configure the vPC domain. You assign the port channel on each device as a peer link, using the same vPC domain ID. For redundancy, we recommend that you should configure at least two of the dedicated ports into the port channel because if one of the interfaces in the vPC peer link fails, the device automatically falls back to use another interface in the peer link.

Note	We recommend that you configure the Layer 2 port channels in trunk mode.

Many operational parameters and configuration parameters must be the same in each device connected by a vPC peer link (see the “Compatibility Parameters for vPC Interfaces” section). Because each device is completely independent on the management plane, you must ensure that the devices are compatible on the critical parameters. vPC peer devices have separate control planes. After configuring the vPC peer link, you should display the configuration on each vPC peer device to ensure that the configurations are compatible.

Note	You must ensure that the two devices connected by the vPC peer link have certain identical operational and configuration parameters. For more information on required configuration consistency, see the “Compatibility Parameters for vPC Interfaces” section.

When you configure the vPC peer link, the vPC peer devices negotiate that one of the connected devices is the primary device and the other connected device is the secondary device (see the “Configuring vPCs” section). The Cisco NX-OS software uses the lowest MAC address to elect the primary device. The software takes different actions on each device—that is, the primary and secondary—only in certain failover conditions. If the primary device fails, the secondary device becomes the new primary device when the system recovers, and the previously primary device is now the secondary device.

You can also configure which of the vPC devices is the primary device. Changing the priority of the vPC peer devices can cause the interfaces in your network to go up and down. If you want to configure the role priority again to make one vPC device the primary device, configure the role priority on both the primary vPC device with a lower priority value and the secondary vPC device with the higher value. Then, shut down the port channel that is the vPC peer link on both devices by entering the shutdown command, and finally reenable the port channel on both devices by entering the no shutdown command.

Note	We recommend that you use two different modules for redundancy on each vPC peer device on each vPC peer link.

The software keeps all traffic that forwards across the vPC peer devices as local traffic. A packet that ingresses the port channel uses one of the local links rather than moving across the vPC peer link. Unknown unicast, multicast, and broadcast traffic (including STP BPDUs) are flooded across the vPC peer link. The software keeps the multicast forwarding state synchronized on both of the vPC peer devices.

You can configure any of the standard load-balancing schemes on both the vPC peer link devices and the downstream device (see the “Configuring Port Channels” chapter for information about load balancing).

Configuration information flows across the vPC peer links using the Cisco Fabric Services over Ethernet (CFSoE) protocol. (See the “vPC and Orphan Ports” section for more information about CFSoE.)

All MAC addresses for those VLANs configured on both devices are synchronized between vPC peer devices. The software uses CFSoE for this synchronization. (See the “vPC and Orphan Ports” section for information about CFSoE.)

If the vPC peer link fails, the software checks the status of the remote vPC peer device using the peer-keepalive link, which is a link between vPC peer devices that ensures that both devices are up. If the vPC peer device is up, the secondary vPC device disables all vPC ports on its device, to prevent loops and disappearing or flooding traffic. The data then forwards down the remaining active links of the port channel.

Note	We recommend that you create and configure a separate VRF and configure a Layer 3 port on each vPC peer device in that VRF for the vPC peer-keepalive link. The default ports and VRF for the peer-keepalive are the management ports and VRF.

The software learns of a vPC peer device failure when the keepalive messages are not returned over the peer-keepalive link.

Use a separate link (vPC peer-keepalive link) to send configurable keepalive messages between the vPC peer devices. The keepalive messages on the vPC peer-keepalive link determines whether a failure is on the vPC peer link only or on the vPC peer device. The keepalive messages are used only when all the links in the peer link fail. See the “Peer-Keepalive Link and Messages” section for information about the keepalive message.

You must manually configure the following features to conform to the primary/secondary mapping of each of the vPC peer devices:

• STP root—Configure the primary vPC peer device as the STP primary root device and configure the vPC secondary device to be the STP secondary root device. See the “vPC Peer Links and STP” section for more information about vPCs and STP.

  • We recommend that you configure the vPC peer link interfaces as STP network ports so that Bridge Assurance is enabled on all vPC peer links

  • We recommend that you configure Rapid per VLAN Spanning Tree plus (PVST+) so that the primary device is the root for all VLANs and configure Multiple Spanning Tree (MST) so that the primary device is the root for all instances.

• Layer 3 VLAN network interface—Configure Layer 3 connectivity from each vPC peer device by configuring a VLAN network interface for the same VLAN from both devices.

• HSRP active—If you want to use Hot Standby Router Protocol (HSRP) and VLAN interfaces on the vPC peer devices, configure the primary vPC peer device with the HSRP active highest priority. Configure the secondary device to be the HSRP standby and ensure that you have VLAN interfaces on each vPC device that are in the same administrative and operational mode. (See the “vPC Peer Links and Routing” section for more information on vPC and HSRP.)

We recommend that you configure Unidirectional Link Detection (UDLD) on both sides of the vPC peer link. See the “Configuring the UDLD Mode” section for information about configuring UDLD.

You can use VLAN network interfaces on the vPC peer devices to link to Layer 3 of the network for such applications as HSRP and PIM. However, we recommend that you configure a separate Layer 3 link for routing from the vPC peer devices, rather than using a VLAN network interface for this purpose.

Ensure that you have a VLAN network interface configured on each peer device and that the interface is connected to the same VLAN on each device. Also, each VLAN interface must be in the same administrative and operational mode. For more information about configuring VLAN network interfaces, see the “Configuring Layer 3 Interfaces” chapter.

If a failover occurs on the vPC peer link, the VLAN interfaces on the vPC peer devices are also affected. If a vPC peer link fails, the system brings down associated VLAN interfaces on the secondary vPC peer device.

You can ensure that specified VLAN interfaces do not go down on the vPC secondary device when the vPC peer link fails.

Use the dual-active exclude interface-vlan command to configure this feature.

Note

When you attach a Layer 3 device to a vPC domain, the peering of routing protocols using a VLAN also carried on the vPC peer link is not supported. If routing protocol adjacencies are needed between vPC peer devices and a generic Layer 3 device, you must use physical routed interfaces for the interconnection. Use of the vPC peer-gateway feature does not change this requirement.

The configuration parameters in this section must be configured identically on both devices of the vPC peer link; otherwise, the vPC moves fully or partially into a suspended mode.

Note	You must ensure that all interfaces in the vPC have the identical operational and configuration parameters listed in this section.

Note	Enter the show vpc consistency-parameters command to display the configured values on all interfaces in the vPC. The displayed configurations are only those configurations that would limit the vPC peer link and vPC from coming up.

The devices automatically check for compatibility for some of these parameters on the vPC interfaces. The per-interface parameters must be consistent per interface, and the global parameters must be consistent globally:

• Port-channel mode: on, off, or active (port-channel mode can, however, be active/passive on each side of the vPC peer)

• Link speed per channel

• Duplex mode per channel

• Trunk mode per channel:

  • Native VLAN

  • VLANs allowed on trunk

  • Tagging of native VLAN traffic

• Spanning Tree Protocol (STP) mode

• STP region configuration for Multiple Spanning Tree

• Enable/disable state per VLAN

• STP global settings:

  • Bridge Assurance setting

  • Port type setting

  • Loop Guard settings

• STP interface settings:

  • Port type setting

  • Loop Guard

  • Root Guard

• Maximum Transmission Unit (MTU)

If any of these parameters are not enabled or defined on either device, the vPC consistency check ignores those parameters.

Note	To ensure that none of the vPC interfaces are in the suspend mode, enter the show vpc brief and show vpc consistency-parameters commands and check the syslog messages.

When any of the following parameters are not configured identically on both vPC peer devices, a misconfiguration might cause undesirable behavior in the traffic flow:

• MAC aging timers

• Static MAC entries

• VLAN interface—Each device on the end of the vPC peer link must have a VLAN interface configured for the same VLAN on both ends and they must be in the same administrative and operational mode. Those VLANs configured on only one device of the peer link do not pass traffic using the vPC or peer link. You must create all VLANs on both the primary and secondary vPC devices, or the VLAN will be suspended.

• All ACL configurations and parameters

• Quality of Service (QoS) configuration and parameters

• STP interface settings:

  • BPDU Filter

  • BPDU Guard

  • Cost

  • Link type

  • Priority

  • VLANs (Rapid PVST+)

• Port security

• Cisco Trusted Security (CTS)

• Dynamic Host Configuration Protocol (DHCP) snooping

• Network Access Control (NAC)

• Dynamic ARP Inspection (DAI)

• IP source guard (IPSG)

• Internet Group Management Protocol (IGMP) snooping

• Hot Standby Routing Protocol (HSRP)

• Protocol Independent Multicast (PIM)

• All routing protocol configurations

To ensure that all the configuration parameters are compatible, we recommend that you display the configurations for each vPC peer device once you configure the vPC.

You can configure the graceful consistency check feature, which suspends only the links on the secondary peer device when a mismatch is introduced in a working vPC. This feature is configurable only in the CLI and is enabled by default.

Use the graceful consistency-check command to configure this feature.

As part of the consistency check of all parameters from the list of parameters that must be identical, the system checks the consistency of all VLANs.

The vPC remains operational, and only the inconsistent VLANs are brought down. This per-VLAN consistency check feature cannot be disabled and does not apply to Multiple Spanning Tree (MST) VLANs.

LACP uses the system MAC address of the vPC domain to form the LACP Aggregation Group (LAG) ID for the vPC. (See the “Configuring Port Channels” chapter for information about LAG-ID and LACP.)

You can use LACP on all the vPC port channels, including those channels from the downstream device. We recommend that you configure LACP with active mode on the interfaces on each port channel on the vPC peer devices. This configuration allows you to more easily detect compatibility between devices, unidirectional links, and multihop connection, and provides dynamic reaction to run-time changes and link failures.

We recommend that you manually configure the system priority on the vPC peer link devices to ensure that the vPC peer link devices have a higher LACP priority than the downstream connected devices. A lower numerical value system priority means a higher LACP priority.

Note	When manually configuring the system priority, you must ensure that you assign the same priority value on both vPC peer devices. If the vPC peer devices have different system priority values, vPC does not come up.

Although vPCs provide a loop-free Layer 2 topology, STP is still required to provide a fail-safe mechanism to protect against any incorrect or defective cabling or possible misconfiguration. When you first bring up a vPC, STP reconverges. STP treats the vPC peer link as a special link and always includes the vPC peer link in the STP active topology.

We recommend that you set all the vPC peer link interfaces to the STP network port type so that Bridge Assurance is automatically enabled on all vPC peer links. We also recommend that you do not enable any of the STP enhancement features on vPC peer links. If the STP enhancements are already configured, they do not cause any problems for the vPC peer links..

When you are running both MST and Rapid PVST+, ensure that the PVST simulation feature is correctly configured.

See the Cisco Nexus 9000 Series NX-OS Layer 2 Switching Configuration Guide for information about STP enhancement features and PVST simulation.

Note	You must configure a list of parameters to be identical on the vPC peer devices on both sides of the vPC peer link. See the “Compatibility Parameters for vPC Interfaces” section for information about these required matched settings.

STP is distributed; that is, the protocol continues running on both vPC peer devices. However, the configuration on the vPC peer device elected as the primary device controls the STP process for the vPC interfaces on the secondary vPC peer device.

The primary vPC device synchronizes the STP state on the vPC secondary peer device using Cisco Fabric Services over Ethernet (CFSoE). See the “vPC and Orphan Ports” section for information about CFSoE.

The STP process for vPC also relies on the periodic keepalive messages to determine when one of the connected devices on the peer link fails. See the “Peer-Keepalive Link and Messages” section for information about these messages.

The vPC manager performs a proposal/handshake agreement between the vPC peer devices that set the primary and secondary devices and coordinates the two devices for STP. The primary vPC peer device then controls the STP protocol on both the primary and secondary devices. We recommend that you configure the primary vPC peer device as the STP primary root device and configure the secondary VPC device to be the STP secondary root device.

If the primary vPC peer device fails over to the secondary vPC peer device, there is no change in the STP topology.

The BPDUs uses the MAC address set for the vPC for the STP bridge ID in the designated bridge ID field. The vPC primary device sends these BPDUs on the vPC interfaces.

You must configure both ends of vPC peer link with the identical STP configuration for the following parameters:

• STP global settings:

  • STP mode

  • STP region configuration for MST

  • Enable/disable state per VLAN

  • Bridge Assurance setting

  • Port type setting

  • Loop Guard settings

• STP interface settings:

  • Port type setting

  • Loop Guard

  • Root Guard

Note	If any of these parameters are misconfigured, the Cisco NX-OS software suspends all interfaces in the vPC. Check the syslog and enter the show vpc brief command to see if the vPC interfaces are suspended.

Ensure that the following STP interface configurations are identical on both sides of the vPC peer links or you may see unpredictable behavior in the traffic flow:

• BPDU Filter

• BPDU Guard

• Cost

• Link type

• Priority

• VLANs (PVRST+)

Note	Display the configuration on both sides of the vPC peer link to ensure that the settings are identical.

You can use the show spanning-tree command to display information about the vPC when that feature is enabled. See the Cisco Nexus 9000 Series NX-OS Layer 2 Switching Configuration Guide for an example.

Note	We recommend that you configure the ports on the downstream devices as STP edge ports. You should configure all host ports connected to a switch as STP edge ports. See the Cisco Nexus 9000 Series NX-OS Layer 2 Switching Configuration Guide for more information about STP port types.

The vPC peer switch feature was added to Cisco NX-OS to address performance concerns around STP convergence. This feature allows a pair of Cisco Nexus 9000 Series devices to appear as a single STP root in the Layer 2 topology. This feature eliminates the need to pin the STP root to the vPC primary switch and improves vPC convergence if the vPC primary switch fails.

To avoid loops, the vPC peer link is excluded from the STP computation. In vPC peer switch mode, STP BPDUs are sent from both vPC peer devices to avoid issues related to STP BPDU timeout on the downstream switches, which can cause traffic disruption.

This feature can be used with the pure peer switch topology in which the devices all belong to the vPC.

Note

Peer-switch feature is supported on networks that use vPC and STP-based redundancy is not supported. If the vPC peer-link fail in a hybrid peer-switch configuration, you can lose traffic. In this scenario, the vPC peers use the same STP root ID as well as the same bridge ID. The access switch traffic is split in two with half going to the first vPC peer and the other half to the second vPC peer. With peer link failure, there is no impact to the north/south traffic but the east/west traffic is lost.

See the Cisco Nexus 9000 Series NX-OS Layer 2 Switching Configuration Guide for information about STP enhancement features and Rapid PVST+.

A feature was added to Cisco NX-OS to address table synchronization across vPC peers using the reliable transport mechanism of the Cisco Fabric Service over Ethernet (CFSoE) protocol. You must enable the ip arp synchronize and ipv6 nd synchronize commands to support faster convergence of address tables between the vPC peers. This convergence overcomes the delay that occurs in ARP table restoration for IPv4 or ND table restoration for IPv6 when the peer link port channel flaps or when a vPC peer comes back online.

Note	You can use the mode auto command to automatically enable this feature. See the “Enabling Certain vPC Commands Automatically” section for information about using this command.

The Cisco NX-OS software for the Nexus 9000 Series devices does not support Product Independent Multicast (PIM), Source-Specific Multicast (SSM) or Bidirectional (BIDR) on a vPC. The Cisco NX-OS software fully supports PIM Any Source Multicast (ASM) on a vPC.

The software keeps the multicast forwarding state synchronized on both of the vPC peer devices. The IGMP snooping process on a vPC peer device shares the learned group information with the other vPC peer device through the vPC peer link; the multicast states are always synchronized on both vPC peer devices. The PIM process in vPC mode ensures that only one of the vPC peer devices forwards the multicast traffic to the receivers.

Each vPC peer is a Layer 2 or Layer 3 device. Multicast traffic flows from only one of the vPC peer devices. You might see duplicate packets in the following scenarios:

• Orphan hosts

• When the source and receivers are in the Layer 2 vPC cloud in different VLANs with multicast routing enabled and a vPC member link goes down.

You might see negligible traffic loss in the following scenarios:

• When you reload the vPC peer device that is forwarding the traffic.

• When you restart PIM on the vPC peer device that is forwarding the traffic.

Ensure that you dual-attach all Layer 3 devices to both vPC peer devices. If one vPC peer device goes down, the other vPC peer device continues to forward all multicast traffic normally.

The following outlines vPC PIM and vPC IGMP/IGMP snooping:

• vPC PIM—The PIM process in vPC mode ensures that only one vPC peer device forwards multicast traffic. The PIM process in vPC mode synchronizes the source state with both vPC peer devices and elects which vPC peer device forwards the traffic.

• vPC IGMP/IGMP snooping—The IGMP process in vPC mode synchronizes the designated router (DR) information on both vPC peer devices. Dual DRs are available for IGMP when you are in vPC mode. Dual DRs are not available when you are not in vPC mode, because both vPC peer devices maintain the multicast group information between the peers.

Note

A PIM neighbor relationship between a vPC VLAN (a VLAN that is carried on a vPC peer link) and a downstream vPC-attached Layer 3 device is not supported, which can result in dropped multicast packets. If a PIM neighbor relationship is required with a downstream Layer 3 device, a physical Layer 3 interface must be used instead of a vPC interface.

You should enable or disable IGMP snooping identically on both vPC peer devices, and all the feature configurations should be identical. IGMP snooping is on by default.

Note	The following commands are not supported in vPC mode: ip pim spt-threshold infinity ip pim use-shared-tree-only

See the Cisco Nexus 9000 Series NX-OS Multicast Routing Configuration Guide for more information about multicasting.

By default, a multicast router sends PIM joins upstream only if it has interested receivers. These interested receivers can either be IGMP hosts (they communicate through IGMP reports) or other multicast routers (they communicate through PIM joins).

In the Cisco NX-OS vPC implementation, PIM works in dual designated router (DR) mode. That is, if a vPC device is a DR on a vPC SVI outgoing interface (OIF), its peer automatically assumes the proxy DR role. IGMP adds an OIF (the report is learned on that OIF) to the forwarding if the OIF is a DR. With dual DRs, both vPC devices have an identical (*,G) entry with respect to the vPC SVI OIFs as shown in this example:

VPC Device1:
------------
(*,G)
oif1 (igmp)
VPC Device2:
------------
(*,G)
oif1 (igmp)

When the multicast source is in a Layer 3 cloud (outside the vPC domain), one vPC peer is elected as the forwarder for the source. This forwarder election is based on the metrics to reach the source. If there is a tie, the vPC primary is chosen as the forwarder. Only the forwarder has the vPC OIFs in its associated (S,G) and the nonforwarder (S,G) has 0 OIFs. Therefore, only the forwarder sends PIM (S,G) joins toward the source as shown in this example:

VPC Device1 (say this is Forwarder for Source 'S'):
------------
(*,G)
oif1 (igmp)
(S,G)
oif1 (mrib)
VPC Device2:
------------
(*,G)
oif1 (igmp)
(S,G)
NULL

In the case of a failure (for example, a Layer 3 Reverse Path Forwarding (RPF) link on the forwarder becomes inoperable or the forwarder gets reloaded), if the current nonforwarder ends up becoming the forwarder, it has to start sending PIM joins for (S,G) toward the source to pull the traffic. Depending upon the number of hops to reach the source, this operation might take some time (PIM is a hop-by-hop protocol).

To eliminate this issue and get better convergence, use the ip pim pre-build-spt command. This command enables PIM send joins even if the multicast route has 0 OIFs. In a vPC device, the nonforwarder sends PIM (S,G) joins upstream toward the source. The downside is that the link bandwidth upstream from the nonforwarder gets used for the traffic that is ultimately dropped by it. The benefits that result with better convergence far outweigh the link bandwidth usage. Therefore, we recommend that you use this command if you use vPCs.

The First Hop Routing Protocols (FHRPs) interoperate with vPCs. The Hot Standby Routing Protocol (HSRP), and Virtual Router Redundancy Protocol (VRRP) all interoperate with vPCs. We recommend that you dual-attach all Layer 3 devices to both vPC peer devices.

The primary FHRP device responds to ARP requests, even though the secondary vPC device forwards the data traffic.

To simplify initial configuration verification and vPC/HSRP troubleshooting, you can configure the primary vPC peer device with the FHRP active router highest priority.

In addition, you can use the priority command in the if-hsrp configuration mode to configure failover thresholds for when a group state enabled on a vPC peer link is in standby or in listen state. You can configure lower and upper thresholds to prevent the interface from going up and down.

VRRP acts similarly to HSRP when running on vPC peer devices. You should configure VRRP the same way that you configure HSRP.

When the primary vPC peer device fails over to the secondary vPC peer device, the FHRP traffic continues to flow seamlessly.

We recommend that you configure routing adjacency between the two vPC peer devices to act as a backup routing path. If one vPC peer device loses Layer 3 uplinks, the vPC can redirect the routed traffic to the other vPC peer device and leverage its active Layer 3 uplinks.

You can configure the inter-switch link for a backup routing path in the following ways:

• Create a Layer 3 link between the two vPC peer devices.

• Use the non-VPC VLAN trunk with a dedicated VLAN interface.

• Use a vPC peer link with a dedicated VLAN interface.

We do not recommend that you configure the burnt-in MAC address option (use-bia) for HSRP or manually configure virtual MAC addresses for any FHRP protocol in a vPC environment because these configurations can adversely affect vPC load balancing. The HSRP use-bia option is not supported on vPCs. When you are configuring custom MAC addresses, you must configure the same MAC address on both vPC peer devices.

You can use the delay restore command to configure a restore timer that delays the vPC coming back up until after the peer adjacency forms and the VLAN interfaces are back up. This feature enables you to avoid packet drops when the routing tables might not be converged before the vPC is once again passing traffic. Use the delay restore command to configure this feature.

To delay the VLAN interfaces on the restored vPC peer device from coming up, use the interfaces-vlan option of the delay restore command.

See the Cisco Nexus 9000 Series NX-OS Unicast Routing Configuration Guide for more information about FHRPs and routing.

This section describes best practices for using and configuring Layer 3 with vPC.

The Cisco Fabric Services over Ethernet (CFSoE) is a reliable state transport mechanism that is used to synchronize the actions of the vPC peer devices. CFSoE carries messages and packets for many features linked with vPC, such as STP and IGMP. Information is carried in CFS/CFSoE protocol data units (PDUs).

When you enable the vPC feature, the device automatically enables CFSoE, and you do not have to configure anything. CFSoE distributions for vPCs do not need the capabilities to distribute over IP or the CFS regions. You do not need to configure anything for the CFSoE feature to work correctly on vPCs.

The CFSoE transport is local to each VDC.

You can use the show mac address-table command to display the MAC addresses that CFSoE synchronizes for the vPC peer link.

Note	Do not enter the no cfs eth distribute or the no cfs distribute command. You must enable CFSoE for vPC functionality. If you do enter either of these commands with vPC enabled, the system displays an error message.

When you enter the show cfs application command, the output displays “Physical-eth,” which shows the applications that are using CFSoE.

CFS also transports data over TCP/IP. See the Cisco Nexus 9000 Series NX-OS System Management Configuration Guide for more information about CFS over IP.

Note	The software does not support CFS regions.

When a device that is not vPC-capable connects to each peer, the connected ports are known as orphan ports because they are not members of a vPC. The device’s link to one peer will be active (forwarding) and the other link will be standby (blocking) due to STP.

If a peer link failure or restoration occurs, an orphan port’s connectivity might be bound to the vPC failure or restoration process. For example, if a device’s active orphan port connects to the secondary vPC peer, the device loses any connections through the primary peer if a peer link failure occurs and the vPC ports are suspended by the secondary peer. If the secondary peer were to also suspend the active orphan port, the device’s standby port becomes active, provides a connection to the primary peer, and restores connectivity. You can configure in the CLI that specific orphan ports are suspended by the secondary peer when it suspends its vPC ports and are restored when the vPC is restored.

You can configure the Cisco Nexus 9000 Series device to restore vPC services when its peer fails to come online by using the auto-recovery command. You must save this setting in the startup configuration. On reload, if the peer link is down and three consecutive peer-keepalive messages are lost, the secondary device assumes the primary STP role and the primary LACP role. The software reinitializes the vPCs, bringing up its local ports. Because there are no peers, the consistency check is bypassed for the local vPC ports. The device elects itself to be the STP primary regardless of its role priority and also acts as the master for LACP port roles.

Note	You can use the mode auto command to automatically enable this feature. See the“Enabling Certain vPC Commands Automatically” section for information about using this command.

When the other peer device completes its reload and adjacency forms, the following process occurs:

1. The first vPC peer maintains its current role to avoid any transition reset to other protocols. The peer accepts the other available role.

2. When an adjacency forms, consistency checks are performed and appropriate actions are taken.

1.    configure terminal


2.    vpc domain domain-id


3.    reload restore [delay time-out]


4.    exit


5.    show running-config vpc


6.    show vpc consistency-parameters interface port-channel number


7.    copy running-config startup-config

switch# configure terminal
switch(config)#

switch(config)# vpc domain 5
switch(config-vpc-domain)#

switch(config-vpc-domain)# reload restore

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

switch# show running-config vpc

switch# show vpc consistency-parameters
interface port-channel 1

switch# copy running-config startup-config

switch# configure terminal
Enter configuration commands, one per line. End with CNTL/Z.
switch(config)# vpc domain 5
switch(config-vpc-domain)# reload restore

Warning:
Enables restoring of vPCs in a peer-detached state after reload, will wait for 240
seconds (by default) to determine if peer is un-reachable

switch(config-vpc-domain)# exit
switch(config)# exit
switch# copy running-config startup-config
switch# show running-config vpc

!Command: show running-config vpc
!Time: Wed Mar 24 18:43:54 2010
version 5.0(2)
feature vpc
logging level vpc 6
vpc domain 5
reload restore

switch# show vpc consistency-parameters interface port-channel 1

Legend:
Type 1 : vPC will be suspended in case of mismatch
Name Type Local Value Peer Value
------------- ---- ----------- ---------------
STP Port Type 1 Default -
STP Port Guard 1 None -
STP MST Simulate PVST 1 Default -
mode 1 on -
Speed 1 1000 Mb/s -
Duplex 1 full -
Port Mode 1 trunk -
Native Vlan 1 1 -
MTU 1 1500 -
Allowed VLANs - 1-3967,4048-4093
Local suspended VLANs

1.    configure terminal


2.    vpc domain domain-id


3.    auto-recovery [reload-delay time]


4.    exit


5.    show running-config vpc


6.    show vpc consistency-parameters interface port-channel number


7.    copy running-config startup-config

switch# configure terminal
switch(config)#

switch(config)# vpc domain 5
switch(config-vpc-domain)#

switch(config-vpc-domain)# auto-recovery

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

switch# show running-config vpc

switch# show vpc consistency-parameters
interface port-channel 1

switch# copy running-config startup-config

switch# configure terminal
Enter configuration commands, one per line. End with CNTL/Z.
switch(config)# vpc domain 5
switch(config-vpc-domain)# auto-recovery

Warning:
Enables restoring of vPCs in a peer-detached state after reload, will wait for 240
seconds to determine if peer is un-reachable

switch(config-vpc-domain)# exit
switch(config)# exit
switch# copy running-config startup-config

Before You Begin

Ensure that you have enabled the vPC feature.

Note	When using a non-VPC dedicated trunk link between the VPC peers, the non-VPC VLANs should have a different global priority on the peers to prevent STP from blocking the VLANs.

1.    configure terminal


2.    vpc domain domain-id


3.    peer-switch


4.    spanning-tree vlan vlan-range priority value


5.    exit


6.    show spanning-tree summary


7.    copy running-config startup-config

switch# configure terminal
switch(config)#

switch(config)# vpc domain 5
switch(config-vpc-domain)#

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

switch(config)# spanning-tree vlan 1
priority 8192

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

switch# show spanning-tree summary

switch# copy running-config startup-config

switch# configure terminal
Enter configuration commands, one per line. End with CNTL/Z.
switch(config)# vpc domain 5
switch(config-vpc-domain)# peer-switch

2010 Apr 28 14:44:44 switch %STP-2-VPC_PEERSWITCH_CONFIG_ENABLED: vPC peer-switch
configuration is enabled. Please make sure to configure spanning tree "bridge" priority as
per recommended guidelines to make vPC peer-switch operational.

switch(config-vpc-domain)# spanning-tree vlan 1 priority 8192
switch(config-vpc-domain)# exit
switch(config)#

1.    configure terminal


2.    spanning-tree pseudo-information


3.    vlan vlan-id designated priority priority


4.    vlan vlan-id root priority priority


5.    vpc domain domain-id


6.    peer-switch


7.    exit


8.    show spanning-tree summary


9.    copy running-config startup-config

switch# configure terminal
switch(config)#

switch(config)# spanning-tree pseudo-information
switch(config-pseudo)#

switch(config-pseudo)# vlan 1 designated
priority 8192

switch(config-pseudo)# vlan 1 root
priority 4096

switch(config)# vpc domain 5
switch(config-vpc-domain)#

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

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

switch# show spanning-tree summary

switch# copy running-config startup-config

switch# configure terminal
Enter configuration commands, one per line. End with CNTL/Z.
switch(config)# spanning-tree pseudo-information
switch(config-pseudo)# vlan 1 designated priority 8192
switch(config-pseudo)# vlan 1 root priority 4096
switch(config-pseudo)# vpc domain 5
switch(config-vpc-domain)# peer-switch
switch(config-vpc-domain)# exit
switch(config)#