vpcEXEC

show vpc brief

Displays a summary of the vPC status, including domain ID, peer link status, and consistency parameters.

Overview

The 'show vpc brief' command is a fundamental diagnostic tool for Cisco NX-OS Virtual Port Channel (vPC) technology. vPC allows a single logical port channel to span two Nexus switches, providing redundancy and increased bandwidth while eliminating the need for Spanning Tree Protocol (STP) blocking. This command provides a concise summary of the vPC domain status, including peer adjacency, keepalive connectivity, configuration consistency, and role. It is typically the first command used when verifying vPC operation after configuration or during troubleshooting. On Cisco NX-OS, vPC requires a dedicated peer link (a port-channel) and a keepalive link (usually a separate Layer 3 path, such as the management interface). The command output quickly indicates whether the two switches have formed a vPC domain and if the necessary parameters are synchronized. In troubleshooting workflows, 'show vpc brief' helps isolate issues: if peer status is down, check the peer link; if keepalive is down, check the keepalive link; if consistency fails, investigate mismatched configurations. Understanding this output is essential for network engineers managing data center environments with Nexus switches.

Syntax·EXEC

show vpc brief

When to Use This Command

Quickly verify the operational state of a vPC domain after configuration.
Troubleshoot vPC peer link or keepalive failures.
Check consistency of vPC parameters between peer switches.
Monitor vPC role (primary/secondary) and compatibility status.

Parameters

Parameter	Syntax	Required	Description
brief	brief	Optional	Optional keyword to display a summarized view of the vPC domain. Without it, 'show vpc' provides more detailed information.

Command Examples

Healthy vPC Domain

show vpc brief

Legend:
                (*) - local vPC is down, forwarding via vPC peer-link

vPC domain id                     : 10
Peer status                       : peer adjacency formed ok
vPC keep-alive status             : peer is alive
Configuration consistency status  : success
Per-vlan consistency status       : success
Type-2 consistency status         : success
vPC role                          : primary
Number of vPCs configured         : 5
Peer Gateway                      : Enabled
Dual-active excluded VLANs        : -
Graceful Consistency Check        : Enabled
Auto-recovery status              : Enabled (timeout = 240 seconds)
Delay-restore status              : Timer is off (timeout = 30s)
Delay-restore SVI status          : Timer is off (timeout = 10s)
Operational Layer3 Peer-router    : Disabled

All status fields show success or healthy values. Peer adjacency is formed, keepalive is alive, consistency checks pass, role is primary, and 5 vPCs are configured.

vPC Peer Link Down

show vpc brief

Legend:
                (*) - local vPC is down, forwarding via vPC peer-link

vPC domain id                     : 10
Peer status                       : peer link is down
vPC keep-alive status             : peer is alive
Configuration consistency status  : success
Per-vlan consistency status       : success
Type-2 consistency status         : success
vPC role                          : primary
Number of vPCs configured         : 5
Peer Gateway                      : Enabled
Dual-active excluded VLANs        : -
Graceful Consistency Check        : Enabled
Auto-recovery status              : Enabled (timeout = 240 seconds)
Delay-restore status              : Timer is off (timeout = 30s)
Delay-restore SVI status          : Timer is off (timeout = 10s)
Operational Layer3 Peer-router    : Disabled

Peer status shows 'peer link is down' indicating a problem with the vPC peer link (e.g., port-channel down). Keepalive is still alive, so the issue is isolated to the peer link.

Understanding the Output

The 'show vpc brief' output provides a high-level summary of the vPC domain health. The first line 'Peer status' indicates whether the peer adjacency is formed over the peer link. A healthy state shows 'peer adjacency formed ok'. If the peer link is down, it will show 'peer link is down'. The 'vPC keep-alive status' shows if the peer is reachable via the keepalive link (usually a separate Layer 3 path). 'Configuration consistency status' checks that global vPC parameters (like VLANs, MTU) match between peers. 'Per-vlan consistency status' ensures VLAN configurations are consistent. 'Type-2 consistency status' checks for type-2 parameters (e.g., STP, ACLs). All should show 'success' for proper operation. 'vPC role' indicates whether this switch is primary or secondary. 'Number of vPCs configured' shows how many vPC interfaces are defined. Other fields like 'Peer Gateway', 'Dual-active excluded VLANs', and 'Auto-recovery' show feature statuses. Problem values include 'peer link is down', 'peer is not reachable' for keepalive, or 'failed' for consistency checks. A healthy domain shows all success statuses and a formed peer adjacency.

Configuration Scenarios

Basic vPC Domain Setup

Two Nexus switches (Nexus-A and Nexus-B) configured as a vPC domain with a peer link and keepalive link.

Topology

   Nexus-A ---- peer-link ---- Nexus-B
      |                        |
   keepalive (mgmt0)    keepalive (mgmt0)
      |                        |
   Access switch (vPC member port)

Steps

1.Configure vPC domain on both switches with same domain ID.
2.Create peer link port-channel and add member interfaces.
3.Configure keepalive link (e.g., using mgmt0 or a routed interface).
4.Create vPC member port-channels on both switches with same vPC ID.

Configuration

! Nexus-A
vpc domain 10
  role priority 1000
  peer-keepalive destination 10.1.1.2 source 10.1.1.1
  peer-gateway
  auto-recovery
interface port-channel1
  switchport mode trunk
  vpc peer-link
interface Ethernet1/1
  channel-group 1 mode active
! Nexus-B
vpc domain 10
  role priority 2000
  peer-keepalive destination 10.1.1.1 source 10.1.1.2
  peer-gateway
  auto-recovery
interface port-channel1
  switchport mode trunk
  vpc peer-link
interface Ethernet1/1
  channel-group 1 mode active

Verify: Run 'show vpc brief' on both switches. Verify peer status is 'peer adjacency formed ok', keepalive is 'peer is alive', and consistency status is 'success'.

Watch out: Ensure the peer link is a trunk port and the keepalive uses a separate Layer 3 path; using the same link for both can cause split-brain scenarios.

Troubleshooting with This Command

When troubleshooting vPC issues on Cisco NX-OS, 'show vpc brief' is the starting point. If 'Peer status' shows 'peer link is down', check the peer link port-channel: ensure the member interfaces are up and the port-channel is not err-disabled. Use 'show interface port-channel1' and 'show port-channel summary' to verify. If 'vPC keep-alive status' shows 'peer is not reachable', check the keepalive link: verify IP connectivity between the keepalive source and destination addresses, and ensure the keepalive interface is up. If 'Configuration consistency status' shows 'failed', use 'show vpc consistency-parameters' to identify mismatched parameters (e.g., VLANs, MTU, STP settings). Resolve inconsistencies by aligning configurations on both peers. If 'vPC role' is not as expected (e.g., both switches show secondary), check the role priority configuration; the switch with lower priority becomes primary. Also, note that vPC member ports may be suspended if consistency fails; check 'show vpc brief' for the number of vPCs configured and compare with 'show vpc' for per-vPC status. In dual-active scenarios (both switches become primary), the keepalive link is critical; ensure it is functioning. The command also shows 'Auto-recovery status' and 'Delay-restore' timers, which can affect recovery after failures. Always verify both switches' outputs to ensure they agree.

CCNA Exam Tips

Remember that 'show vpc brief' is the first command to check vPC health; always look for 'peer adjacency formed ok' and consistency 'success'.

In CCNP exams, know that vPC keep-alive uses a separate Layer 3 link (often mgmt0 or a routed interface) and is not the same as the peer link.

Be aware that 'Configuration consistency status' failure can cause vPC to suspend member ports; check 'show vpc consistency-parameters' for details.

Common Mistakes

Confusing 'peer link' with 'keepalive link'; the peer link carries data traffic, keepalive is only for heartbeat.

Assuming 'vPC role' indicates which switch is active for all traffic; both switches forward traffic for their own vPC member ports.

Ignoring consistency failures; even if peer link is up, inconsistency can cause traffic blackholing.

Platform Notes

On Cisco NX-OS, 'show vpc brief' is available in all Nexus platforms (e.g., 3000, 5000, 7000, 9000 series). The output is consistent across versions, though newer versions may add fields like 'Operational Layer3 Peer-router'. In contrast, Cisco IOS (e.g., Catalyst 6500 with VSS) uses 'show switch virtual' or 'show etherchannel summary' for similar redundancy concepts, but vPC is unique to NX-OS. On Arista (MLAG), the equivalent is 'show mlag' or 'show mlag brief'. On Juniper (MC-LAG), 'show configuration protocols lacp' and 'show interfaces ae0 extensive' are used. For Cisco NX-OS, ensure the vPC feature is enabled ('feature vpc') before using this command. Also, note that the command can be executed in any EXEC mode; no privilege level restrictions.

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