Learning All About Router

This lab will introduce the Cisco Internetwork Operating System (IOS) command line interface (CLI). You will need to logon to a router and become familiar with the different levels of access on the router. You will also become familiar with the commands available to you in each mode (user or privileged) and the router help facility, history, and editing features.
Show Version
The 'show version' command gives you a lot more information than at first you may think. Use 'show version' to obtain critical information, such as: router platform type, operating system revision, operating system last boot time and file location, amount of memory, number of interfaces, and configuration register.
Router>show version
Krang Operating System SoftwareRouter
uptime is 2 minutesSystem returned to
ROM by power-onSystem image file is "flash:c2500.bin"
[[[OUTPUT DELETED]]]
1 Ethernet/IEEE 802.3 interface(s)
1 Serial(sync/async) network interface(s)
1 ISDN Basic Rate interface(s)
32K bytes of non-volatile configuration memory.
4096K bytes of processor board System flash (Read/Write)
Configuration register is 0x2102
Routing Protocols
To view the status of any routing protocols currently configured on the router, use the 'show protocols' command.
Router>show protocols
Global values:
Internet Protocol routing is enabled
BRI0 is administratively down, line protocol is Down
Ethernet0 is administratively down, line protocol is Down
Serial0 is administratively down, line protocol is Down


Flash Memory
Flash memory is a special kind of memory on the router that contains the operating system image file(s). Unlike regular router memory, Flash memory continues to maintain the file image even after power is lost.
Router>show flash


System flash directory:
File Length Name/status1 3015588 c2500.bin
[3015652 bytes used, 1178652 available, 4194304 total]
4096K bytes of processor board System flash (Read/Write)

Running Configuration
The currently active configuration script running on the router is referred to as the 'running-config' on the routers command-line interface. Note the privilege mode required. The running configuration script is not automatically saved on a Cisco router, and will be lost in the event of power failure. The running configuration must be manually saved with the 'copy' command (discussed in a later lab).
Router>
Router>enable
Router#show running-configBuilding configuration...
Current configuration:
!version 12.0
!hostname Router
!interface Serial0
no ip address
shutdown
!interface BRI0
no ip address
shutdown
!interface Ethernet0
no ip address
shutdown
!line con 0
line aux 0
line vty 0 4
!end
Router#


Command History
The routers Command Line Interface (CLI) maintains by default the last 10 commands you have entered in memory, for later retrieval. You can change this default value. You cycle through previous router commands entered (since the last power loss), using one of two methods. To view all of the past commands still in router memory at the same time, use the 'show history' command. For single line retrieval, use either the Arrow-Up (for previous command) and Arrow-Down (for next command), or Control-P (for previous command) and Control-N (for next command).
Router>show history
show version
show protocols
show flashenable
show running-configdisable
show history


Clock
The router keeps its own clock that you can use to synchronize devices to. To view the clock use the show clock command.
Krang#show clock
*00:38:35.755 UTC Mon Mar 1 1993
Krang#

Host Table
You can create a list of host name on your router. You can view the entries (if any) by typing show hosts.
Krang#show hosts
Default domain is not setName/address lookup uses static mappings
Host Flags Age Type Address(es)Krang#
Show users
The show users command displays users who are connected to the router.
Krang#show users
Line User Host(s) Idle Location
* 0 con 0 idle 00:00:00
Krang#


Show Interfaces
The show interfaces command will display statistics for all interfaces configured on the router
Krang#show interfaces
BRI0 is administratively down, line protocol is down
Hardware is BRI
MTU 1500 bytes, BW 64 Kbit, DLY 20000 usec, rely 255/255, load 1/255
Encapsulation HDLC, loopback not setLast input never, output never, output hang never
Last clearing of "show interface" counters never
Input queue: 0/75/0 (size/max/drops); Total output drops: 0
Queueing strategy: weighted fair
Output queue: 0/1000/64/0 (size/max total/threshold/drops)
Conversations 0/0/256 (active/max active/max total)
Reserved Conversations 0/0 (allocated/max allocated)5 minute input rate 0 bits/sec, 0 packets/sec5 minute output rate 0 bits/sec, 0 packets/sec0 packets input, 0 bytes, 0 no bufferReceived 0 broadcasts, 0 runts, 0 giants, 0 throttles0 input errors, 0 CRC, 0 frame, 0 overrun, 0 ignored, 0 abort0 packets output, 0 bytes, 0 underruns0 output errors, 0 collisions, 5 interface resets0 output buffer failures, 0 output buffers swapped out0 carrier transitions--More--



Notice the --More-- This means that there is more information pertaining to the last command. To view more commands line by line, press: enter To exit the output and return to the router prompt, press: e (this can be any letter, it's just easy to remember that e is for exit) To view more output one screen at a time, press the space bar
Show Protocols
The show protocols displays global and interface specific status of layer 3 protocols.
Krang#show protocols
Global values:
Internet Protocol routing is enabled
BRI0 is administratively down, line protocol is down
Ethernet0 is administratively down, line protocol is down
Serial0 is administratively down, line protocol is down
Serial1 is administratively down, line protocol is down
Serial2 is administratively down, line protocol is down

Copyright (c) 2001 Boson Software, Inc. All Rights Reserved.