Download Cisco Router Show Command Explained with Examples DOCX

Show command is the most powerful command in Cisco IOS. It lists running configuration and
provides valuable information for troubleshooting. Information provided by this command will be
static. It will not update until we execute the same command again. In this article we will explain
show command with examples.
We will use Packet Tracer network simulator software for demonstration. Beside Packet Tracer
You can also use any other network simulator software such as Boson, GNS or even better if you
can afford, use a real Cisco device. No matter what option you choose, till this uses Cisco IOS
output will be same.
Create a network topology as illustrate in following figure
Initial configuration
Device / Interface
PC0
Router0’s FastEthernet 0/0
Router0’s Serial 0/0/0
Router1’s Serial 0/0/0
Router1’s FastEthernet 0/0
PC1
Connected To
Router0’s FastEthernet 0/0
PC0
Router1’s serial 0/0/0
Router0’s serial 0/0/0
PC1
Router1’s FastEthernet 0/0
IP Address
10.0.0.2/255.0.0.0
10.0.0.1/255.0.0.0
50.0.0.1/255.0.0.0
50.0.0.2/255.0.0.0
20.0.0.1/255.0.0.0
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.
We have created this topology to give you a better overview of show command. You can use single
router if you are unable to replicate this topology in packet tracer. Alternatively you can download
this pre-configured topology from our server. No matter what you prefer, for reset of this article I
assume that you have at least one router available in workspace.
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
UP and UP
UP and Down
Down and Down
Administratively down and down




Description
Interface is operational
Check data link layer for possible reasons given above
Check physical layer for possible reasons given above
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.
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