Helsinki University of Technology
Department of Communications and Networking
Juha Järvinen 10.6.2004
Juha.Jarvinen@netlab.hut.fi
Modified by Zhong Yunqiu 7.8.2008
How to Configure Cisco 2600 Routers
Table of Contents
Purpose ........................................................................................................................3
1 Cisco Inter-network Operating System (IOS)........................................................4
1.1 Cisco IOS Operation Modes............................................................................4
1.1.1 User EXEC Mode ....................................................................................5
1.1.2 Privileged EXEC Mode............................................................................5
1.1.3 Configuration Mode.................................................................................5
1.1.4 No Form ..................................................................................................5
1.2 Getting Help ...................................................................................................6
1.3 Configuration Files .........................................................................................6
1.4 Configuration System (Setup).........................................................................7
1.5 IP Address and Interface Configuration...........................................................7
2 Routing Protocol Configuration............................................................................8
2.1 Routing Information Protocol RIP...................................................................8
2.1.1 RIP Commands........................................................................................8
2.1.2 Specify a RIP Version..............................................................................8
2.1.3 No Form ..................................................................................................9
2.2 Open Shortest Path First OSPF .......................................................................9
2.2.1 OSPF Commands.....................................................................................9
2.2.2 Router ID...............................................................................................10
2.2.3 Virtual Link ...........................................................................................11
2.2.4 Configure OSPF Interface Parameters....................................................11
2.2.5 Configure OSPF authentication..............................................................12
2.2.6 No Form ................................................................................................12
2.3 RIP and OSPF Redistribution........................................................................13
2.3.1 RIP ........................................................................................................13
2.3.2 OSPF .....................................................................................................13
2.3.3 Gateway.................................................................................................13
2.3.4 LAN.......................................................................................................13
3 Configure CEF ...................................................................................................14
3.1 Enable CEF ......................................................................................................14
3.2 Enable Per-Packet Load Balancing ...................................................................14
3.3 Enable Network Accounting for CEF................................................................14
3.4 Verifying CEF..................................................................................................14
References..................................................................................................................15
2
Purpose
Purpose of this document is to show how to use and configure Cisco 2600 Series
routers. Mainly this document has been done for Laboratory work course (S-38.133) at
Networking Laboratory at HUT. On laboratory course these Cisco’s routers are used for
IPv4 routing in small network.
This document includes configuring interfaces up and routing part, which has manual
for RIP (Routing Information Protocol) and for OSPF (Open Shortest Path First). For
other routing protocols among others BGP (Border Gateway Protocol) see for example
Cisco’s web site1.
Chapter 3 is suited very good for example for PC routers running Zebra2 (nowadays
Quagga3) as routing daemon, because it has same commands as Cisco routers use.
Mainly this document is collection of Cisco’s manuals ([1] – [2], [6] – [7]), which are
modified for our laboratory course’s use.
1
www.cisco.com
2
www.zebra.org
3
www.quagga.net
3
1 Cisco Inter-network Operating System (IOS)
1.1 Cisco IOS Operation Modes
The Cisco Software provides access to four different command modes. There are more
commands, but in normal use they are not necessary. Each command mode provides a
different group of related commands. For security purposes, the Cisco IOS software
provides two levels of access to commands: user and privileged. The unprivileged user
mode is called user EXEC mode. The privileged mode is called privileged EXEC mode
and requires a password.
The following table, Table (1) describes four used modes, how to enter the modes and
the resulting prompts. The prompt helps you identify which mode you are in and
therefore which commands are available to you. In Fig. (1) these four operation modes
are presented as a figure.
Table 1. Accessing and Exiting Command Modes.
Command Mode Access Method Prompt Exit Method
User EXEC Log in.
Privileged EXEC From user EXEC
mode, use the enable
EXEC Command
Global configuration From privileged
EXEC mode, use the
configure terminal
privileged EXEC
command.
Interface configuration From global
configuration mode,
specify an interface
using an interface (or
router) command
Router>
Router#
Router(config)# To return to privileged
Router(config-if)#
Or
Router(configrouter)#
Use the logout
command.
To return to user EXEC
mode, use the disable
command
EXEC mode from
global configuration
mode, use the exit or
end command, or press
Ctrl-Z.
To return to global
configuration mode use
the exit command. To
return to privileged
EXEC mode, use the
end command, or press
Ctrl-Z.
4
Router>
enable
Router#
configure
terminal
Router(config)#
interface etc.
Router(config-if)#
Figure 1. Four Cisco IOS Operation modes and their accesses and exits as a figure.
disable
exit,
end,
Ctrl-Z
exit,
end,
Ctrl-Z
exit
1.1.1 User EXEC Mode
When you are connected to the router, you are started in user EXEC mode. The user
EXEC commands are a subset of the privileged EXEC commands.
1.1.2 Privileged EXEC Mode
Privileged commands include the following:
• Configure – Changes the software configuration.
• Debug – Display process and hardware event messages.
• Setup – Enter configuration information at the prompts.
Enter the command disable to exit from the privileged EXEC mode and return to user
EXEC mode.
1.1.3 Configuration Mode
Configuration mode has a set of submodes that you use for modifying interface
settings, routing protocol settings, line settings, and so forth. Use caution with
configuration mode because all changes you enter take effect immediately.
To enter configuration mode, enter the command configure terminal and exit by
pressing Ctrl-Z.
1.1.4 No Form
Almost every configuration command also has a no form. In general, use the no form to
disable a feature or function. Use the command without the keyword no to re-enable a
disabled feature or to enable a feature that is disabled by default. For example, IP
5
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