InterfacesEXEC

show ip interface brief

Displays a summary of all IP interfaces, including their status, protocol state, and IP address.

Overview

The 'show ip interface brief' command is a fundamental tool for any network engineer working with Cisco NX-OS (Nexus) switches and routers. It provides a concise, one-line summary of every interface that has IP routing enabled, displaying the interface name, its assigned IP address (if any), and the operational status of both the line protocol and the link. This command is invaluable for quickly assessing the health of network interfaces, especially in large-scale data center environments where Nexus devices are commonly deployed.

The networking concept behind this command is the OSI model's Layer 1 (physical) and Layer 2 (data link) statuses, combined with Layer 3 (IP) configuration. The 'Interface Status' column actually reflects two distinct states: the first word indicates the line protocol status (Layer 2), which can be 'up', 'down', or 'admin down'. The second word indicates the link state (Layer 1), which can be 'up' or 'down'. For an interface to pass IP traffic, both must be 'up'. An 'admin down' status means the interface has been manually disabled with the 'shutdown' command. A 'down' status without 'admin' indicates a physical problem, such as a disconnected cable, faulty transceiver, or a remote device that is powered off.

On Cisco NX-OS, this command behaves similarly to Cisco IOS but with some nuances. For example, NX-OS supports Virtual Routing and Forwarding (VRF), and you can filter the output to a specific VRF using the 'vrf' keyword. Additionally, NX-OS may display VLAN interfaces (SVI) and loopback interfaces alongside physical ports. The command is often the first step in troubleshooting connectivity issues: if an interface is not 'up/up', you can then use more detailed commands like 'show interfaces' or 'show interface <interface>' to investigate further. It also helps in verifying IP addressing consistency, especially after configuration changes. In summary, 'show ip interface brief' is a quick, essential command for any Nexus administrator to get a snapshot of interface status and IP configuration.

Syntax·EXEC

show ip interface brief [vrf <vrf-name>] [interface <interface-type> <interface-number>]

When to Use This Command

Quickly verify which interfaces are up/up and have IP addresses assigned.
Identify interfaces that are administratively down or have protocol issues.
Check IP addressing consistency across a switch or router.
Troubleshoot connectivity issues by confirming interface status and IP configuration.

Parameters

Parameter	Syntax	Required	Description
vrf	vrf <vrf-name>	Optional	Specifies the VRF (Virtual Routing and Forwarding) instance to display interfaces for. If omitted, interfaces from all VRFs are shown. Use this to focus on a specific VRF, such as 'management' or 'default'.
interface	interface <interface-type> <interface-number>	Optional	Limits the output to a specific interface, such as 'Ethernet1/1' or 'Vlan100'. Useful for checking a single interface without scrolling through the full list.

Command Examples

Basic show ip interface brief

show ip interface brief

Interface       IP Address      Interface Status
Lo0             10.1.1.1/32     up            up
Eth1/1          192.168.1.1/24  up            up
Eth1/2          unassigned      down          down
Eth1/3          10.2.2.1/24     admin down    down
Vlan100         172.16.1.1/24   up            up

Each line shows an interface, its IP address (or 'unassigned'), the line protocol status (Interface Status), and the link state (Protocol Status). 'up/up' means both are operational; 'admin down' means the interface was manually disabled.

Show IP interface brief for a specific VRF

show ip interface brief vrf management

Interface       IP Address      Interface Status
mgmt0           10.10.10.1/24   up            up

Filters output to only interfaces in the specified VRF (e.g., management VRF).

Understanding the Output

The output of 'show ip interface brief' on Cisco NX-OS displays a table with three columns: Interface, IP Address, and Interface Status (which actually shows both line protocol and link state). The Interface column lists the interface name (e.g., Ethernet, Loopback, VLAN). The IP Address column shows the configured IP address and subnet mask in CIDR notation, or 'unassigned' if no IP is configured. The Interface Status column shows two values separated by a space: the first indicates the line protocol status (up, down, admin down) and the second indicates the link state (up, down). A healthy interface shows 'up up' for both. 'admin down' indicates the interface was manually shut down. 'down' indicates a physical or Layer 1 issue. For troubleshooting, focus on interfaces that are not 'up up' – these indicate potential problems. Note that NX-OS may also include a 'Protocol Status' column in some versions, but typically it's combined. This command is essential for a quick health check of all IP interfaces.

Configuration Scenarios

Verifying Interface Status After Configuration

After configuring IP addresses on multiple interfaces, you need to confirm they are all up and operational.

Topology

Nexus 9000 switch with three interfaces: Eth1/1 connected to a router, Eth1/2 connected to a server, and Eth1/3 unused.

Steps

1.Configure IP addresses on Eth1/1 and Eth1/2.
2.Ensure the interfaces are not shut down.
3.Run 'show ip interface brief' to verify status.

Configuration

! Configuring IP addresses
interface Ethernet1/1
  ip address 192.168.1.1/24
  no shutdown
interface Ethernet1/2
  ip address 10.1.1.1/24
  no shutdown
interface Ethernet1/3
  shutdown

Verify: Run 'show ip interface brief' and check that Eth1/1 and Eth1/2 show 'up up' and Eth1/3 shows 'admin down'.

Watch out: If Eth1/1 shows 'up down', the cable might be disconnected or the remote device is off. Check physical connectivity.

Troubleshooting with This Command

When troubleshooting connectivity issues on Cisco NX-OS, 'show ip interface brief' is often the first command to run. It quickly reveals which interfaces are not in the desired 'up/up' state. For example, if a host cannot reach a gateway, check the SVI (Vlan interface) status. If the SVI shows 'down/down', the VLAN may not exist or the corresponding Layer 2 interface is down. If it shows 'admin down', the SVI was manually disabled. For physical interfaces, 'down/down' indicates a Layer 1 problem (cable, transceiver, or remote device). 'up/down' is rare but can indicate a Layer 2 issue like a spanning tree blocking state. In NX-OS, you can also use the 'vrf' parameter to isolate issues within a specific VRF. For instance, if management access is lost, run 'show ip interface brief vrf management' to check the mgmt0 interface. If the interface is 'up/up' but you still cannot ping, the issue might be routing or ACLs. The command is also useful for verifying that IP addresses are correctly assigned after configuration changes. Remember that loopback interfaces are always 'up/up' unless administratively shut down, so they are reliable for testing. In summary, this command is the starting point for any interface-related troubleshooting on Nexus devices.

CCNA Exam Tips

Memorize that 'admin down' means the interface was manually disabled with 'shutdown'.

Understand that 'up/up' is the desired state; anything else indicates a problem.

Know that 'show ip interface brief' is faster than 'show interfaces' for a summary view.

Common Mistakes

Confusing 'Interface Status' with 'Protocol Status' – both must be 'up' for the interface to be operational.

Forgetting that loopback interfaces are always 'up/up' unless administratively shut down.

Assuming 'unassigned' means the interface is not working – it just has no IP address.

Platform Notes

On Cisco NX-OS, 'show ip interface brief' is similar to Cisco IOS but with some differences. NX-OS supports VRFs, so you can filter by VRF. The output format may vary slightly between NX-OS versions; some versions include a separate 'Protocol Status' column, while others combine it with 'Interface Status'. On IOS, the command is 'show ip interface brief' as well, but IOS does not support the 'vrf' parameter (instead, you use 'show ip interface brief vrf <name>' in some IOS versions). On NX-OS, the command also shows management interfaces (mgmt0) by default, which is not always the case in IOS. For equivalent commands on other platforms: on Juniper JunOS, use 'show interfaces terse'; on Arista EOS, use 'show ip interface brief' (similar to Cisco). On NX-OS, the command is available in all modes (EXEC, privileged EXEC). Note that in some NX-OS versions, the command may be 'show ip interface brief' or 'show ip interface brief | include up' for filtering. Always check the specific NX-OS version documentation for exact syntax.

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