This tutorial explains basic show commands (such as show ip route, show ip interfaces brief, show version, show flash, show running-config, show startup-config, show controllers, etc.) in Cisco router with examples. Learn how to use show commands in Cisco router to get specific information.
To explain basic router show commands, I will use packet tracer network simulator software. You can use any network simulator software or can use a real Cisco router to follow this guide. There is no difference in output as long as your selected software contains the commands explained in this tutorial.
Create a practice lab as shown in following figure or download this pre-created practice lab and load in packet tracer
Download practice topology for basic show commands
If require, you can download the latest as well as earlier version of Packet Tracer from here. Download Packet Tracer
In this practice lab
| Device / Interface | Connected To | IP Address |
| PC0 | Router0's FastEthernet 0/0 | 10.0.0.2/255.0.0.0 |
| Router0's FastEthernet 0/0 | PC0 | 10.0.0.1/255.0.0.0 |
| Router0's Serial 0/0/0 | Router1's serial 0/0/0 | 50.0.0.1/255.0.0.0 |
| Router1's Serial 0/0/0 | Router0's serial 0/0/0 | 50.0.0.2/255.0.0.0 |
| Router1's FastEthernet 0/0 | PC1 | 20.0.0.1/255.0.0.0 |
| PC1 Router1's | FastEthernet 0/0 | 20.0.0.2/255.0.0.0 |
- RIP Routing protocol is configured on both routers.
- Clock rate and bandwidth is assigned on Router0’s serial interface 0/0/0.
Above practice lab is only a recommendation to understand the show commands more clearly, it’s not a requirement to follow this tutorial. You can follow this tutorial in a single router or even without router.
Basic Cisco Router Show Commands
Access CLI prompt of router
Use enable command to enter in privilege exec mode. Cisco IOS supports unique context sensitive help features. We can use this features to list all available commands and parameters those are associated with show command.
Enter show command with ? ( Question mark ) to list all available commands
If prompt returns with parameters excluding <CR> that means it requires more parameters to complete this command.
If prompt returns with <CR> only as option, that means router does not need any additional parameters to complete this command. You can execute this command in current condition.
Router#show interfaces
This command shows the status and configuration of interfaces. By default it will display all interfaces. But you can limit it to particular interface. To view the detail of specific interface you can use the following command.
Router#show interface [type slot_# port_#]
For example to view the detail of serial 0/0/0 interface on Router0 we will use following command
Output of this command provides several details about interface including its status, encapsulation, interface type, MTU, last input and output packet etc. First line of output shows the status of interface. First up indicates the status of physical layer. Second up refers the data link layer status.
Possible status of physical layer
- UP: - Interface is receiving physical layer signals.
- Down:- Interface is not receiving physical layer signals. This could be happen due to following reasons.
- Cable is unplugged
- You are using wrong cable type.
- Attached device is turned off.
- Administratively down:- Interface is turned off by using shutdown command.
Possible status of data link layer
- UP:- interface is operational.
- Down:- interface is not operational. This could be due to following reasons:-
- Physical layer is down
- Incorrect encapsulation setting
- Incorrect clock rate or bandwidth setting
- Incorrect keepalives setting
| Interface status | Description |
| UP and UP | Interface is operational |
| UP and Down | Check data link layer for possible reasons given above |
| Down and Down | Check physical layer for possible reasons given above |
| Administratively down and down | Interface is disabled with shutdown command |
- Second line shows the Hardware type and MAC address of interface.
- Third line shows the IP address of interface.
- MTU indicates the Ethernet frame size.
- BW parameter refers to bandwidth link
Router# show ip interface brief
This command provides a quick overview of all interfaces on the router including their IP addresses and status.
Router#show controllers [type slot_# port_#]
This command is used to check the hardware statistic of interface including clock rate and cable status such as cable is attached or not. One end of serial cable is physically DTE, and other end is DCE. If cable is attached, it will display the type of cable.
Router#show flash
This command will display the content of flash memory, used space and available space. By default router stores IOS image file in flash. We can use this command to check the available space in Flash memory while updating / restoring IOS files.
Router#show version
This command will display information about software version of running IOS. It also provides information about configuration setting. It shows current configuration register setting that is used to reset the password of router.
Router#show startup-config
Routers load configuration from NVRAM in startup. This command will display the configuration stored in NVRAM.
Router#show running-config
Router keeps all running configuration in RAM. This command will display the configuration currently running in RAM.
Router#show clock
This command displays current time on router.
Router#show hosts
This command displays names and addresses of the hosts on the network that you can connect.
Router#show users
This command displays users currently connected to the router.
Router#show arp
This command displays ARP cache table. ARP table is used to resolve the hardware MAC addresses.
Router#show protocols
This command shows the status of configured layer three protocols on the device.
Router#show history
Router keeps a history of used command. This command will list the used command on that level.
Router#show ip route
Routers use routing table to take packet forward decision. This command displays routing table.
Show command supports several other parameters to display command specific information. Due to length of this article we will include them in next articles with their respective topics.
