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.
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. I need to install 6 routers in my emulator with 6 serial interfaces in each router to do the lab for the CCIE book I purchased. I load CSR1000v-universalk9.16.5.1b-serial yet it only offers 4 Ethernet interfaces. The settings are set to Cisco default. Serialport = serial.Serial(2, baudrate=9600, timeout=None, parity=serial.PARITYNONE, bytesize=serial.EIGHTBITS, stopbits=serial.STOPBITSONE, xonxoff=False) The next two lines clear any lingering input into the receive queue that we aren’t interested in and then print the name of the port we’re using. Cisco WIC-2T 2-Port Serial Wan Interface Card (Renewed) $40.00 Works and looks like new and backed by the Amazon Renewed Guarantee. Frequently bought together + + Total price: $109.30. Add all three to Cart Add all three to List. These items are shipped from and sold by different sellers.
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
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 |
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.
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.
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.
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.
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 |
This command provides a quick overview of all interfaces on the router including their IP addresses and status.
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.
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.
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.
Routers load configuration from NVRAM in startup. This command will display the configuration stored in NVRAM.
Router keeps all running configuration in RAM. This command will display the configuration currently running in RAM.
This command displays current time on router.
This command displays names and addresses of the hosts on the network that you can connect.
This command displays users currently connected to the router.
This command displays ARP cache table. ARP table is used to resolve the hardware MAC addresses.
This command shows the status of configured layer three protocols on the device.
Router keeps a history of used command. This command will list the used command on that level.
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.