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InterfacesPrivileged EXEC

show ip interface brief

Displays a summary of all IP interfaces on the device, including their IP address, status, and protocol state, used for quick verification of interface configuration and connectivity.

Syntax·Privileged EXEC
show ip interface brief

When to Use This Command

  • Quickly verify which interfaces are up/up and have IP addresses assigned after a configuration change.
  • Troubleshoot why a specific interface is not passing traffic by checking its status and protocol state.
  • Document the current IP addressing scheme on a router or switch for inventory or audit purposes.
  • Identify interfaces that are administratively down or have no IP address assigned.

Command Examples

Basic usage on a router with multiple interfaces

show ip interface brief
Interface              IP-Address      OK? Method Status                Protocol
GigabitEthernet0/0     192.168.1.1     YES NVRAM  up                    up      
GigabitEthernet0/1     10.0.0.1        YES NVRAM  up                    up      
Serial0/0/0            172.16.0.1      YES NVRAM  up                    up      
Serial0/0/1            unassigned      YES NVRAM  administratively down down    
Loopback0              1.1.1.1         YES NVRAM  up                    up      
Vlan1                  192.168.10.1    YES NVRAM  up                    up

Interface: Name of the interface. IP-Address: Configured IP address or 'unassigned'. OK?: Indicates if the interface is verified (YES/NO). Method: How the IP was configured (NVRAM, DHCP, manual). Status: Line protocol status (up/down/administratively down). Protocol: IP protocol state (up/down).

Checking interfaces on a switch

show ip interface brief
Interface              IP-Address      OK? Method Status                Protocol
Vlan1                  192.168.10.1    YES NVRAM  up                    up      
Vlan10                 10.10.10.1      YES NVRAM  up                    up      
GigabitEthernet0/1     unassigned      YES unset  up                    up      
GigabitEthernet0/2     unassigned      YES unset  down                  down

On a switch, only SVIs (Vlan interfaces) typically have IP addresses. Physical ports show 'unassigned'. Status 'down' indicates no link, while 'up' means link is active. Protocol 'down' on a physical port usually means no cable or device connected.

Understanding the Output

The 'show ip interface brief' command provides a concise table of all interfaces with IP configuration. The 'Interface' column lists the interface name. 'IP-Address' shows the assigned IP address or 'unassigned' if none. 'OK?' indicates whether the interface passed a basic verification (always YES on modern IOS). 'Method' shows how the IP was obtained (e.g., NVRAM for static, DHCP, manual). 'Status' reflects the line protocol state: 'up' means the interface is operational, 'down' indicates a physical or data link issue, and 'administratively down' means the interface was manually disabled with 'shutdown'. 'Protocol' indicates the IP protocol state: 'up' means IP is enabled and the interface is ready to route, 'down' means IP is not operational (often due to line protocol being down). In troubleshooting, look for interfaces that show 'administratively down' (need 'no shutdown'), 'down/down' (cable or peer issue), or 'up/down' (Layer 1 up but Layer 2 or IP issue).

CCNA Exam Tips

1.

Remember that 'administratively down' means the interface was manually disabled with the 'shutdown' command; you need 'no shutdown' to bring it up.

2.

On a switch, only SVIs (Vlan interfaces) will have IP addresses; physical ports show 'unassigned' unless they are routed ports.

3.

The 'Status' column refers to Layer 1 (physical) and Layer 2 (data link); 'Protocol' refers to Layer 3 (IP). 'up/up' is fully operational.

4.

If an interface shows 'up/down', suspect a Layer 2 issue like mismatched encapsulation or keepalive failure.

Common Mistakes

Confusing 'administratively down' with a physical problem; always check if the interface was intentionally shut down.

Assuming 'unassigned' means the interface is not working; it simply means no IP is configured, which is normal for Layer 2 switchports.

Overlooking that 'show ip interface brief' does not show IPv6 addresses; use 'show ipv6 interface brief' for IPv6.

Related Commands

show interfaces

Displays detailed status and statistics for all interfaces or a specific interface, used to verify interface operational state, errors, and performance.

show ip interface

Displays the status and configuration of all IP interfaces on a Cisco router, including IP address, protocol status, and interface statistics, used for verifying interface IP configuration and troubleshooting connectivity issues.

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