Computer Networks

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Computer Networks

• Project 5
• Router and Switch Configuration

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TABLE OF CONTENTS

• Project Overview
• Report Format
• Before You Get Started
• Know Your Hardware
• What you will Configure
• Configuring a Router
• Configuring a Switch
• Configuring a Host
• So, does it work?
• Running ping
• Running traceroute

With special thanks to Mike Cole for his help
with configuration and knowledge transfer. He
showed me how to make this work!
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Project Overview

• The purpose of this Project is to become learn
  how to set a router and a switch in order to
  produce a network configuration of your choosing.
• You will do this by using a commercial router- a
  Cisco Catalyst 5500, a commercial switch a
  Cisco Catalyst 2900, and the various hosts in the
  Network lab.
• When you are finished, you will have a network
  made up of various subnets and will be able to
  communicate between the various hosts that are
  located on different subnets.
• You can work on this either singly or in pairs.
• Have fun.

Report Format
As in the last Project, there is no formal report
that needs to be produced. However, you will be
asked questions about this Project on the final
exam. It would be wise to be prepared.
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Before You Get Started

• So whats the bigger picture here? To give you
  some idea of the scope of routers, please answer
  the following questions before you get to the
  lab. If you do so, this will all make a lot more
  sense to you.
• Whats the difference between a router, a switch,
  and a hub?
• Cisco is one manufacturer of core routers. Who
  else makes routers? This does NOT mean home
  modem routers.
• What operating system is run on the Cisco
  routers?
• Having learned the operating system, look up the
  following information
• Name the routine protocols supported by the OS.
• Briefly describe how to use the on-line help
  feature of the OS user interface.
• You may find this site useful
• http//www.cisco.com/univercd/cc/td/doc/product/so
  ftware/ios11/cbook/cip.htm
• d) How do you configure a node?? Read about
  ifconfig and you too will be an expert. What is
  a Class A, B and C address?

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Environment and Tools
Getting Around You can log into any of the
machines Net2 Net5 via terminal/monitor.
Warning, Net2 is very slow and will be used only
indirectly in this lab. You can ssh between any
of the machines net1 net5 by using their IP
address we arent running a nameserver so you
will not be able to do something like ping
Net2. Saving data between the Networks Lab and
the rest of the world During the course of doing
these various measurements, youll be collecting
a lot of data. This data will be output from
Ethereal, various other outputs, and so on. But
theres no printing or saving facilities in the
lab. So you would really like to get the data
back to your home directory in the regular CS lab
to get your file back to spears. From any of
the machines, you can ssh to tarski (also called
Net1), the machine that sees the world. ssh b
192.168.1.1 l Being able
to ssh in this fashion may or may not be useful
to you. What IS useful is being able to copy
files between nodes. Suppose Im on net2 and I
want to transfer the file CollectedWisdom to my
home directory on Spears. I do that with the
command scp which you can look up. Heres an
example of its use scp CollectedWisdom
jbreecher_at_192.168.1.1CollectedWisdom This will
deposit the file Collected Wisdom in my home
directory.
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Know Your Hardware
Connection to switch goes in output 1 of row 3.
VLans/Subnets are configured on the left-most 5
connectors.
Cisco Catalyst 2900 Switch
Power cord to wall this is how you turn it off!!
Connection from router goes in right-most input,
port 24.
Serial connector goes directly to serial port on
Net4
Our router is a bit different from the picture
Slot 1 Controls a switch internal to the
router Slot 2 Controls router Slot 3 10/100
RJ45 ports connect to the internal switch Slot 4
Fibre ports not used in this lab
Cisco Catalyst 5500 Router
Power switch this is how you turn the router
off and on!!
The router is highly available. In this case it
means that you can pull the card in slot 4 and
the router will keep on ticking. Its
hot-pluggable.
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Configuration Chart
Router VLan1 VLan2
VLan3 VLan4 VLan5
Dont mess 192.X.B.1 155.X.C.1
150.X.D.1 13.X.37.1
With this 255.255.255.0 255.255.255.0
255.255.254.0 255.255.0.0 192.168.1.2
The meaning of the letters in the IP addresses is
given in the next slide.
Connection To World 140.232.101.139
Red Wire
Switch 192.168.1.3 Vlan 1 Vlan 2
VLan 3 Vlan 4
VLan 5 Port 1 Port 2
Port 3 Port 4
Port 5
Tarski
192.168.1.1 255.255.255.0

• 192.X.B.5
• 255.255.255.0

155.X.C.5 255.255.255.0
13.X,55.5 255.255.0.0
150.X.D1,5 255.255.255.0
NET1 This machine has two NICs
NET4
NET5
NET2
NET3
All nodes have username / password root /
NetLab Note that by running root you have
complete control over the machine.
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What You Will Configure
The goal is to have a different configuration for
each of you. So that if someone leaves the
router and switch in THEIR configuration, youll
get to start from scratch. If youre working in
pairs, what you should do is obvious.
Breecher 37
123 111 120

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Procedure

• Turn off the power to the router and the switch.
  The router has a knob to turn the switch you
  turn off by pulling the plug.
• Pull off the 5 cables between the switch and the
  nodes youre going to be reattaching them in a
  way different from the people who came before you
  anyway.
• Hook up the serial connector of Net4 to the
  router via the serial cable there are two
  serial connections on the back of Net4 use the
  top one.
• Hook up the red wire between the router and the
  switch.
• Turn on the power to the router and the switch.
  It can take several minutes for the router to
  boot.
• Get minicom working on Net4 see Appendix A for
  this later directions for configuration assume
  that this is working correctly.
• Configure the router using the methods described
  below.
• Configure the switch using the methods described
  below.
• Configure the nodes using the methods described
  below.
• Run the various tests showing the nodes connect
  to each other.
• Take apart all the wires. This means the serial
  cable, the red wire, and unhook all the Netx
  wires from the switch.

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Configuring A Router
WHAT ARE YOU DOING?? The purpose here is to
configure a set of IP addresses that have access
to the back plane of the router. If you have
that access, then you can communicate with the
other IP addresses on this backplane and can get
to any of the hosts associated with their subnets.
Im going to use in this example the addresses I
assigned myself
A VLan is the same as a subnet. Think of each
VLan as a door weve configured here the
addresses that can go out on each of the VLans.
You KNOW the router is fully powered up when the
large light on the left side of slot 2 is green
Router Backplane
VLan1 192.168.1.2 255.255.255.0
VLan2 192.37.123.1 255.255.255.0
VLan5 13.37.37.1 255.255.0.0
VLan4 150.37.120.1 255.255.254.0
VLan3 155.37.111.1 255.255.255.0
Dont mess With this VLan1
So a node with an address in the range
150.37.120.0 - 192.37.121.255 can get to the
router backplane thru VLan4 (note its subnet
mask!!) Once on the backplane, that signal can be
sent to any of the other VLans. So a node having
an address in the range 13.37.0.0 13.37.255.255
will see the frame via VLan5. This is our task
here to connect various subnets together even
if those subnets have very different IP addresses.
All the VLan outputs are multiplexed together and
run out through the RED WIRE to the switch.
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Configuring A Router

• Make sure you have the serial cable configured
  between the router and Net4. Make sure the
  router is turned on.
• From the net4 command line, you should be able to
  say minicom see Appendix A for any problems.
• There should be no password required at this
  point. If nothing happens, its either the
  minicom configuration (App. A) or you forgot to
  turn the power on the router.
• Now youre ready to configure the router.
• en
  // Enable supervisor mode
• password Cisco // Note
  its an uppercase C
• Help
  // Just so you see what it gives you
• Show run //
  Shows the current configuration. Shows that
  current vlan1 is enabled and no others //
  are enabled.
• // NOTE DO NOT MESS with
  vlan1 this is how you telnet into the switch
  you // change vlan1 and youre in deep
  doodoo!!
• The task now is to assign the e-net addresses to
  the Vlans these represent the addresses that
  will allow access to the bus on the router. If
  this confuses you, go back to the picture on the
  previous page.
• Config t
  // Starts cycle to be performed for
  each vlan
• Interface vlan2
  // The vlan youre configuring in this
  cycle
• Ip address 192.37.123.1 255.255.255.0 // use
  your assigned addresses here
• No shutdown
• End
• // Repeat steps 9
  - 13 so that you give addresses to all vlan2
  vlan5.
• // NOTE the
  router may suddenly spit back all kinds of
  configuration info at you do not be
  // alarmed!!
• Show run
  // You should see router is set up according to
  your specification

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Configuring A Router

• Try these other commands to see what they do
• Show ip route
  // shows routing tables (no rip or ospf)
• show interfaces,
  // contains among other things throughput
  information
• show protocols
  // Sow that IP is running on the Vlans
• Show arp
• Show ?
• AT any time you can turn off the power on the
  router. If the whole world seems screwed up,
  this is a way out. Then when you turn the power
  on, youll be back in a clean and original state.
• There are lots of commands we arent using
  because our router isnt connected to another
  router.

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Configuring A Switch
So heres that red wire from the router it
contains everything we know and need to know.
What matters is the left-most 5 ports those are
the only ones that have been previously
configured to be active on this switch. Our task
is simple to associate/map the VLans to these
output ports. So were assigning VLans to ports.
VLan1 is already mapped to Port 1 please dont
mess with that. So you will map VLan2 VLan5 to
ports 2 5 in any order. See the example.
EXAMPLE Suppose I associate VLan5 with port 2.
That means, as seen on a previous page, that the
node that is wired to port2 must have IP
addresses in the range 13.37.0.013.37.255.255
/255.255.0.0. This simply means that the node
must be on the same subnet as the port in the
router
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Configuring A Switch

• // Now youre ready to configure the switch But
  first you need to log onto the switch.
  // Remember, we last left you logged on the
  router so you need to get from the router to
  // the switch..
• At the router command line, Do a ping to
  192.168.1.3 if it doesnt work you probably
  forgot to turn on the switch. Do it now and be
  patient. Router command line, telnet to
  192.168.1.3 this is the IP of the switch. The
  password required here is password. Now that
  youre logged on to the switch, you can do its
  configuration.
• En
  // Enable supervisor mode
• Password password // This
  gets you to the privileged part of the command
  set
• ?
  // Just so you see what it gives you
• Show running //
  Shows the current configuration only Vlan1 is
  active
• config T
• int f0/2
  // Were configuring Port 2
• Switchport access vlan 5 //
  Associating VLan5 with this port2
• Speed 100
  // try this possibilities are 10Mbps, and 100
  Mbps.
• Duplex full
  // Choices are half or full what happens if you
  do this? What // happens if
  you say half?
• End
• Repeat steps 6 11 until all the ports are
  configured.
• Show run
• 
  //If the switch ever asks you to save the
  configuration, say no.
• Q quit
  // leave the switch
• Are there other switch commands????

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Configuring A Node

• The goal here is to get our nodes, Net2 Net5 to
  be able to talk to the router and to the other
  nodes. This involves two actions
• Configuring the IP address of the node this
  needs to be an address that is in the subnet of
  the appropriate router port.
• Setting the route table so that the node knows
  what to do with any particular address.
• The first step is to figure out what possible IP
  addresses can be used on any of the nodes. Net1
  we havent messed with its 192.168.1.1
  thats why it should be on port 1 of the switch
  since that leads to VLan1 which traces back to
  the router address 192.168.1.4/255.255.255.0.
• Its your task to do similar thinking for the
  other Nodes.
• As another example, Ive put VLan5 connected to
  port2. Lets suppose I plugged the cable from
  Net4 into port2. That means that Net4 has to be
  in the subnet of VLan5 hope youve followed
  that logic, since you need to do that for your
  own configuration. Id recommend you make
  yourself a little table.

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Configuring A Node

• Useful commands for this part include ifconfig,
  route, netstat, and arp.
• There are two interfaces on each node. One is
  called eth0 and is the real physical NIC. The
  other is lo meaning loopback it functions
  only as a way to send a packet to the same node
  without leaving the machine. We want to work
  with eth0.
• Changing the IP address on a node is simple(
  again Im using my example addresses)
• ifconfig eth0 up 13.37.50.50 netmask
  255.255.0.0
• Now go and set Net2 Net5 according to the Table
  youve prepared.
• Do the following steps at Net4
• Ping your router address -- ping 13.37.37.1 ---
  this should work fine because youve told Net4
  that it should send signals out eth0 in order to
  get to anything on its subnet and 13.37.37.1
  is on its subnet as set by the subnet mask.
• Now try pinging to the IP address you set up for
  Net5. Does it work?
• The answer is probably not. The reason it
  doesnt is that your Net4 doesnt know what to do
  with the address. Youve told it, via ifconfig,
  that anything on its subnet goes out eth0, but
  you havent said where anything NOT on the subnet
  should go.
• To do that you need to use the route command.
  Do a man route to become familiar with its
  characteristics. What you need to do is tell
  your Net4 that the way to handle any IP address
  not on the subnet is to send it to the router to
  be handled there. Heres the way to do that
  
• Route add net default gw
  dev eth0
• where you of course have inserted the address of
  the router in the command.
• Use this route command to set the default gateway
  on all the nodes.

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Wed Like To Know It Works
Its very easy to determine if it all works. You
should be able to ping between any two nodes in
your system. Heres a table you should be able
to put a yes into each box if its working
correctly.
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Wed Like To Know It Works

• Run traceroute and see what paths are used for
  your various nodes. How many hops are required
  from Net5 to Net3?
• On the switch reset the speed of two of your
  VLANs to 10Mb/sec.
• Run emma full blast between those two connecting
  nodes. How many bytes per second can you
  transmit. (Appendix B has a review of the emma
  commands). The answer SHOULD be equivalent to 10
  Mb/sec. Make sure you can do that. NOTE if
  you do the command uptime ./emma etc.
  uptime you will get a timing of
  how long it takes to send however many bytes you
  specified.
• Reset the VLans to 100 Mb/sec. You MAY need to
  pull the cables and reinsert them to get the
  nodes to rearbitrate the speeds. Can emma now
  transmit faster? What result do you get?

TURN OFF THE ROUTER AND PULL THE PLUG ON THE
SWITCH!
Useful Commands Ifconfig, route(8), netstat(8),
arp(8), rarp(8), ipchains(8)
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Appendix A - Minicom

• Connecting to the router using minicom
• The Linux product that allows you to use a serial
  connection is called Minicom. Youll find it
  hard to believe, but for many years terminals
  werent connected via a terminal cable but had a
  serial connection. This meant that it was
  necessary to interface the terminal with the
  computer. Life is now simpler were using the
  serial port on the computer to connect with the
  Cisco router.
• Most Linux distributions (i.e. Red Hat) already
  include minicom ours does.
• Start it up with the command "minicom".
• If minicom finds a configuration file, and if
  that configuration file is consistent with the
  settings on the Cisco, youre all set do
  nothing else. Youll see that you have a
  connection to the Cisco youre at a login
  prompt.
• If it doesnt find the correct configuration
  file, then you will need to do these steps
• Press "Ctrl-A Z" to get to the main configuraton
  menu.
• Press "o" to configure minicom.
• Go to "Serial port setup" and make sure that you
  are
• set to the correct "Serial Device" if you
  connected the cable in the top serial connector,
  then this will be /dev/ttyS0
• the speed on line E matches the speed of the
  serial console (this is 9600 for the Cisco)
• Hardware flow control is turned off (NO!) Here
  are the settings I made when using my Serial A /
  COM1 port on my Linux box
• -------------------------------------------------
  ----------------------
• A - Serial Device /dev/ttyS0
  
• B - Lockfile Location /var/lock
  
• C - Callin Program
  

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Appendix B - Emma

• Theres a small program named emma that you will
  be using for TCP tests later on. Heres a
  description of the program that will help you
  later on. Remember way back in Project 0 you
  built a client and server that simply sent
  messages back and forth between each other. This
  program is an offshoot of the code from Project
  0. The code for emma.c is available on all the
  netlab machines.
• Emma has one executable, but it can be run as
  either a sender or a receiver but it does only
  that one instance of the program sends only,
  and the other receives only. Here are the inputs
  for emma
• emma Address
• or UDP
• The program expects switches in a particular
  format. See examples below
• -b - The total bytes to be sent, after
  which sender closes the
• connection. Note the receiver may
  not receive this many bytes.
• -d - Direction - your choices are Send or
  Receive. The receiver also
• does the accept while the Sender
  will do the connect.
• -i - IP Address - in the form
  uuu.vvv.www.xxx. This is needed for the
• Sender/Connector only - it shows how
  to get to the receiver.
• -p - Port that the receiver will accept
  on. Both sides need to know this.
• The default port is built into the
  program - this switch is optional.
• -s - Size of request to be sent or
  received.
• -t - Transport protocol - either TCP
  (default) or UDP
• Example
• emma -d Send -i 140.232.101.125 -b
  1000000
• emma -d Receive -s 50