Objective: In this lab you’ll configure a simple network to allow two routers to route packets between to remote networks. There is more. The text that is in
bold is the text you really need to type during the lab. Requirements:
- Two Cisco routers with one Ethernet port & one serial port.
- Cisco IOS 10.0 or higher
- One PC for consoling into routers with terminal emulation software
- One serial cable
- One Cisco rollover cable
Setup: Step 1: Physical
Connections Connect the following interfaces:
- Console: Connect your PC/terminal to the console port using a rollover cable & HyperTerminal
(9600-8-N-1-no flow) - Ethernet: Connect Ethernet ports to a hub or a switch using a straight-through cable. Use a cross-over cable if going directly from the
PC’s NIC to the Ethernet (AUI) port on the router using a transceiver. - Serial: If going directly between two routers, do not forget to connect one port via the
DTE cable & the other via the DCE cable.
Step 2: Boot up the routers Just say “no” to use the setup mode (setup dialogue). The setup mode will only
allow you to configure the router with the basic features & not with any advanced features. If asked if you would like to terminate the auto configuration; say “yes”.
Let the routers finish booting.
Step 3: Host Name & Passwords Begin your configuration with the host name & passwords. There is more. This is to remind you of what
router you’re configuring & now’s the time to start thinking about router security.
RouterA
router>en
router#config t Enter configuration
commands, one per line. End with CNTL/Z.
router(config)#hostname RouterA (sets the router’s name)
RouterA(config)#enable secret cisco (Sets the
secret password for the router)
RouterA(config)#line vty 0 4 (there are five concurrent connections for the telnet ports coming into a Cisco 2500 router. We
are setting the login password on all five of them)
RouterA(config-line)#login (This enables the router to require a login password for a telnet session to the
router)
RouterA(config-line)#password cisco (this sets the login password for all 5 telnet sessions coming into the router as
cisco)
RouterA(config-line)#exit
RouterA(config)#^Z (This is the key combination of control+z which takes you back to the privileged executive
mode)
RouterA#
RouterB
router>en
router#config t Enter configuration commands, one per line. End with
CNTL/Z.
router(config)#hostname RouterB (sets the router’s name)
RouterB(config)#enable secret cisco (Sets the secret password for the router)
RouterB(config)#line vty 0 4 (there are five concurrent connections for the telnet ports coming into a Cisco 2500 router. We are setting the login password on all five
of them)
RouterB(config-line)#login (This enables the router to require a login password for a telnet session to the
router)
RouterB(config-line)#password cisco (this sets the login password for all 5 telnet sessions coming into the router as
cisco)
RouterB(config-line)#exit
RouterB(config)#^Z (This is the key combination of control+z which takes you back to the privileged executive
mode)
FYI: Anytime you make a configuration change to a router & you come back to the privileged exec mode you really need to save your changes to
NVRAM. This ensures that if the router reboots, you will not loose your changes which are in the running-config which is volatile RAM. The following command(s)
saves your changes to the startup-config.
RouterA#copy running-config startup-config
or
RouterA# copy run
start
or
RouterA#wr me (short for write memory)
Step 4: Adding IP Addresses Adding IP addresses, is a basic function of configuring routers.
Below is an example of configuring both an Ethernet & serial interface. For serial interface with the DCE cable you’ll need to also add the clocking with the
clockrate command. Get the IP addresses from the network diagram.
RouterA RouterA#config t Enter configuration commands, one per line. End with
CNTL/Z.
RouterA(config)#int e0
RouterA(config-if)#ip address 172.16.12.1 255.255.255.0
RouterA(config-if)# description LAN Network
for
RouterA RouterA(config-if)# no shutdown
RouterA(config-if)#int s0
RouterA(config-if)#ip address 172.16.10.1 255.255.255.0 (RouterA will
have the serial 0 with the DCE end of the serial cable. The other partner will have serial1 with the DTE end of the serial cable. Check the network diagram to confirm
to see who has what interface)
RouterA(config-if)#clockrate 250000 (DCE interface only which is the s0 on RouterA)
RouterA(config-if)#no
shutdown
RouterA(config-if)#description Network connection to RouterB
RouterB
RouterB#config t Enter configuration commands, one per
line. End with CNTL/Z.
RouterB(config)#int e0
RouterB(config-if)#ip address 172.16.11.1 255.255.255.0
RouterB(config-if)# description LAN
Network for RouterB
RouterB(config-if)# no shutdown
RouterB(config-if)#int s1
RouterB(config-if)#ip address 172.16.10.2
255.255.255.0
RouterB(config-if)#no shutdown
RouterB(config-if)#description Network connection to RouterA
Once both routers are
configured properly, you should be easily able to use the ping command & ping the interface e0 on each of the routers from the neighboring router. If you do a show ip
route on both routers & do not see the directly connected interfaces in the routing table, they’re either not configured or they never came up. Confirm that the IP
addressing took & the interfaces came up by using the show ip int & looking at the interfaces’ status & ip address configuration. RouterA# show ip route
RouterA# show ip int Do this on both routers.
Step 5a: Adding Dynamic Routing: RIP For this router to take part in a dynamic routing using a dynamic
routing protocol like RIP or IGRP, you will need to enable a routing protocol & advertise the directly connected networks that want advertised.. We only advertise the
classful network address, not the subnet mask of the network.
RouterA
RouterA>en RouterA#config t Enter configuration commands, one per line.
End with CNTL/Z. RouterA(config)#router RIP RouterA(config-router)#network 172.16.12.0
RouterB
RouterB>en RouterB#config t Enter
configuration commands, one per line. End with CNTL/Z.
RouterB(config)#router RIP
RouterB(config-router)#network 172.16.11.0
FYI: We
need to advertise the network, not any particular host. An example of that would be enabling RIP on RouterB. We want the other router (RouterA) to know that any
packet destined for the network 172.16.11.0 can be sent to RouterB which has a directly connected 5 entry in it is routing table showing what interface to send the
packet to; in this case its e0. If you route to 172.16.11.1, all your every going to route to, is the e0 on RouterB & nothing else. Test your configuration to ensure
that it’s configured properly by pinging from router to router. Check your routing table for entries that are preceded by a capital letter “R” to ensure that you’re
receiving routing updates using RIP. Ensure that your partner has finished configuring his router so that you can receive his updates. No updates, no ping. Do a
show ip protocol to see what routing protocol is configured on the routers.
Step 5b: Adding Dynamic Routing: IGRP IGRP uses an autonomous system (AS)
number or process id. This number must be the same on all routers wanting to share IGRP routing updates or they do not share. Turn RIP off before you turn on IGRP.
For this lab we will be using an AS number of 100.
RouterA
RouterA>en RouterA#config t
RouterA(config)#no router rip RouterA(config)#router
igrp 100
RouterA(config-router)#network 172.16.12.0 (again, just the network portion of the IP for your Ethernet network, NO subnet
mask)
RouterB
RouterB>en RouterB#config t Enter configuration commands, one per line. End with CNTL/Z.
RouterB(config)#no router
rip
RouterB(config)#router igrp 100
RouterB(config-router)#network 172.16.11.0 (again, your Ethernet network IP NO Subnet Address)
Step
6: Adding Default Routes Good candidates for default routes are routers which are known as the boundary router. This is a router which is normally part of a stub
network. Inside the stub network, the routers may be participating in a dynamic routing using a protocol like RIP, but only a static default route is needed to connect
the stub network to the Internet.
RouterA
RouterA>en RouterA#config t RouterA(config)#ip route 0.0.0.0 0.0.0.0
172.16.10.2
RouterB
RouterB>en RouterB#config t
RouterB(config)#ip route 0.0.0.0 0.0.0.0 172.16.10.1
Step 7: Adding Static
Routes A static route can be often used for different reasons. One reason may be for a router to connect to another router in a lab. You will need to turn off all routing
protocols before you configure the router for static routing.
RouterA
RouterA>en
RouterA#config t
RouterA(config)#no router igrp
100
RouterA(config)#ip route 172.16.11.0 255.255.255.0 172.16.10.2 What we’re saying here is: For RouterA to route to the network 172.16.11.0, go straight to
the next hop interface which is the serial1 (172.16.10.2) attached to RouterB. Since RouterB knows about the directed connected Ethernet network of 172.16.11.0,
it will have route for it in its routing table proceeded by the letter “C”. (See next example)
RouterB#sh ip route (Output omitted) 172.16.0.0/24 is subnetted, 1
subnets C 172.16.0.0 is directly connected, Ethernet0 RouterB# RouterB
RouterB>en
RouterB#
RouterB#config
t
RouterB(config)#no router igrp 100
RouterB(config)#ip route 172.16.12.0 255.255.255.0 172.16.10.1
Step 8: Testing & Monitoring At this
point it’s a good idea 
to start testing your network using various commands. Perform the following on both routers.
RouterA# show ip route
RouterA#
show ip interface brief (This command shows the IP & status of all interface)
RouterA# show controller s0 (Shows whether or not the serial cable is DCE or
DTE.)
RouterA# ping ip-address
RouterA# trace ip-address
RouterA# debug ip rip (Remember to turn debug off when done, use undebug
all, no debug all or un all)
RouterA# terminal monitor (for using debug from a telnet session, otherwise debug output will go straight to the console. Caution: This will
cause the debug output to go straight to all telnet sessions on the router.)
Show commands
RouterA# terminal no monitor(To turn off monitoring
during a telnet session.)
RouterA# show cdp neighbors
RouterA# show ip protocols
RouterA# #show version
RouterA# #show
flash
RouterA# show ip route (shows the routing table)
RouterA# show memory
RouterA# show stacks
RouterA# show
buffers
RouterA# show arp
RouterA# show processes
RouterA# show processes cpu
RouterA# show tech-support
Step 9:
Finishing up Once you have your routers up & working you may wish to run some commands to make working on Cisco routers easier & to stop some of the
default annoying behavior of Cisco routers.
RouterA(config)# ip host RouterB 172.16.10.2 (This configures a host table entry for the name RouterB. So
instead of having to remember the IP of RouterB to ping it, you can now ping it using its name, RouterB. It is the same as using a hosts file on a computer. If you just
type in RouterB & hit enter, the router will assume you are wanting to telnet into RouterB using port 23)
RouterA(config)# no ip domain-lookup (When there is
no DNS server & you miss spell a single word command, it will attempt to do a DNS lookup using a broadcast address of 255.255.255.255. To stop this lookup of a
non-existent DNS server, we can turn off the DNS lookup capability using this command.)
RouterA(config)# banner motd #!!!!Warning! Authorized Access
Only!!!!# (This message will be seen by anyone trying to logon to your router. The # sign is known as a delimiting character & is used to identify the text portion of
the MOTD. Notice that the actual message starts & ends with the delimiting character)
RouterA(config)# no service-config (When you reboot a Cisco
router, the default behavior is to attempt & find a configuration file on the network using a number of methods over a broadcast address of 255.255.255.255. To stop
this annoying behavior, Use this command.)
RouterA(config)#no logging console (Each time you leave one level of the router & return to the previous level
or bring an interface up, you get a read out on the console screen. If you get busy typing & configuring the router this can be distracting & annoying. Use this
command to stop the logging of messages to the console screen.) And do not forget to…
RouterA# show running-config
RouterA# copy
running-config startup-config
Bob Bello, is
the owner of http://www.CiscoKits.com At his site you’ll find over 200 various articles dedicated to
with CCNA & CCNP home lab kits.
