InterfacesEXEC

show ipv6 interface brief

Displays a brief summary of IPv6 interface status and configuration, including IPv6 addresses and operational state.

Overview

The 'show ipv6 interface brief' command is a quick diagnostic tool for IPv6 interface status on Cisco IOS-XR routers. It provides a condensed view of all interfaces with IPv6 enabled, displaying their assigned IPv6 addresses, administrative status, and protocol status. This command is essential for network engineers to verify IPv6 configuration, identify interfaces that are down or missing addresses, and ensure proper connectivity. On IOS-XR, the command supports filtering by interface type and path ID, allowing targeted checks. Unlike the full 'show ipv6 interface' command, the brief version omits detailed information like MTU, neighbor discovery, and timers, making it ideal for rapid assessment. It fits into troubleshooting workflows as a first step: after verifying global routing, use this command to confirm interface-level IPv6 readiness. Platform-specific behavior includes the display of link-local addresses only when explicitly configured; otherwise, they are omitted. The command is also useful for scripting and automation due to its parseable output.

Syntax·EXEC

show ipv6 interface brief [type interface-path-id]

When to Use This Command

Quickly verify all IPv6-enabled interfaces and their addresses after configuration.
Check if an interface has an IPv6 address assigned and is administratively up.
Identify interfaces with no IPv6 address or in down state during troubleshooting.
Monitor IPv6 interface status during network changes or after reload.

Parameters

Parameter	Syntax	Required	Description
type interface-path-id	[type interface-path-id]	Optional	Specifies a particular interface (e.g., GigabitEthernet0/0/0/0). If omitted, all IPv6-enabled interfaces are shown. The interface-path-id follows IOS-XR naming (slot/module/port).

Command Examples

Basic output showing all IPv6 interfaces

show ipv6 interface brief

Interface                      IPv6-Address      Status          Protocol
GigabitEthernet0/0/0/0       2001:db8:1::1/64   Up              Up
GigabitEthernet0/0/0/1       unassigned          Up              Up
Loopback0                     2001:db8:2::1/128  Up              Up
MgmtEth0/0/CPU0/0            fe80::1/64          Up              Up

Each line shows an interface, its IPv6 address (or 'unassigned'), administrative status, and protocol status. 'Up/Up' indicates operational.

Filtering for a specific interface

show ipv6 interface brief GigabitEthernet0/0/0/0

Interface                      IPv6-Address      Status          Protocol
GigabitEthernet0/0/0/0       2001:db8:1::1/64   Up              Up

Output limited to the specified interface, confirming its IPv6 address and operational status.

Understanding the Output

The output consists of four columns: Interface, IPv6-Address, Status, and Protocol. The Interface column lists all interfaces (physical, loopback, management) that have IPv6 enabled. The IPv6-Address column shows the global or unique-local address assigned, or 'unassigned' if none is configured. Link-local addresses (fe80::) are displayed only if explicitly configured or if the interface is up. The Status column indicates the administrative state (Up/Down), and the Protocol column indicates the operational state (Up/Down). A healthy interface shows 'Up' in both Status and Protocol, with a valid IPv6 address. Problematic states include 'Down' in either column (e.g., interface shutdown, no cable, or protocol issues) or 'unassigned' when an address is expected. This command is useful for a quick health check; for detailed information (e.g., neighbor discovery, MTU), use 'show ipv6 interface' without 'brief'.

Configuration Scenarios

Verifying IPv6 on a new interface

After configuring IPv6 on GigabitEthernet0/0/0/2, verify the address and status.

Topology

Router R1 --- Gig0/0/0/2 --- Router R2

Steps

1.Configure IPv6 address on the interface.
2.Use 'show ipv6 interface brief GigabitEthernet0/0/0/2' to confirm.

Configuration

! Configuration on R1
interface GigabitEthernet0/0/0/2
 ipv6 address 2001:db8:3::1/64
 no shutdown
 end

Verify: show ipv6 interface brief GigabitEthernet0/0/0/2 Expected output: Interface Up/Up with address 2001:db8:3::1/64

Watch out: If the interface is not 'no shutdown', Status will be Down. Also ensure the interface is not in a VRF unless specified.

Troubleshooting with This Command

When troubleshooting IPv6 connectivity issues on Cisco IOS-XR, start with 'show ipv6 interface brief' to quickly identify interfaces that are down or missing addresses. If an interface shows Status Down, check if it is administratively shut down ('shutdown' command) or if the line protocol is down due to cable/peer issues. If Status is Up but Protocol is Down, investigate Layer 1 problems (e.g., no cable, wrong SFP) or Layer 2 issues (e.g., VLAN mismatch). If an interface is Up/Up but shows 'unassigned', verify that an IPv6 address is configured under the interface; if not, configure one. For interfaces expected to have a link-local address only, note that IOS-XR does not display them in brief output unless explicitly configured. If an interface has an address but is not communicating, use 'show ipv6 neighbors' to check neighbor reachability. The brief command is also useful after configuration changes or reloads to ensure all interfaces come up correctly. In large networks, filter by interface to avoid overwhelming output.

CCNA Exam Tips

Remember that 'Status' is administrative (shutdown/no shutdown) and 'Protocol' is operational (line protocol).

On IOS-XR, link-local addresses are not shown by default unless explicitly configured; they appear only if the interface is up.

The command can be filtered by interface to reduce output; useful in exams with many interfaces.

Common Mistakes

Confusing 'Status' and 'Protocol' columns; Status is admin state, Protocol is line protocol.

Assuming 'unassigned' means no IPv6 configured; it could also mean only link-local address (not shown).

Forgetting that management interfaces (MgmtEth) are included; they may have IPv6 addresses.

Platform Notes

On Cisco IOS-XR, the 'show ipv6 interface brief' command differs from classic IOS in several ways. IOS-XR uses a different interface naming convention (e.g., GigabitEthernet0/0/0/0 vs GigabitEthernet0/0). The output does not include link-local addresses by default; they appear only if explicitly configured with the 'ipv6 address fe80::... link-local' command. In classic IOS, link-local addresses are always shown. Additionally, IOS-XR supports filtering by interface, which classic IOS does not for this command. The command is available in EXEC mode; no privilege escalation needed. On other platforms like Juniper Junos, the equivalent is 'show interfaces terse' with IPv6 filtering. On Cisco IOS-XE, the command is similar to classic IOS but uses the same naming as IOS-XR. Version differences: In older IOS-XR releases (e.g., 4.x), the command may not support filtering; in newer releases (6.x+), it does. Always check the specific version documentation.

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