Chapter Eleven
Networking
with TCP/IP
and the Internet
IP Planning
An IP address contains 32 bits or total of 4
octets

i.e. 192.168.0.2
Each bit of the 32 bits can be a member of one
and only one of the following sections:
Network
 Host
 Subnet
What is the Network section?

A group Identifier (compare to area code
number)
What is the Host section?
 Group of individual PC’s or devices within
the same network

IP Planning
How many bits should be under the Network section?
 Depending on the size of the organization and potential
growth, one of the following classes can be obtained from the
ICANN organization: A, B, or C
How many bits should belong to the host section?
 32 – # Network bits
How many hosts can a Network have?
 (2 ^ Number of host bits ) - 2
IP Planning
Why are we loosing 2?
Network Identifier
 Network Broadcast Address
What is a Network Identifier?


The first IP address in a network, known as the “cable
identifier”. Represents the entire network. All host bits are
turned off (0’s)
 Example: 192.168.4.0
 What class is it? What is it in binary?
What is a Broadcast Address?
 The last IP address in a network. Used to communicate with
all the hosts in the network. All host bits are turned on
(1’s)
 Example: 192.168.4.255
What is it in binary?
IP Planning
Examples:



Class A uses the first 8 bits for the network identifier
 The address range is only up to 126. The binary equivalent to that is
01111110. The MSB is 0 so we use only the last 7 bits.
 Number of networks that can be created = 27 = 128 – 2 = 126. Why?
 Number of hosts per Class A network
 32 bits – 8 bits = 24 bits
 224 = 16,777,216 – 2 = 16,777,214
 Class A structure: N.H.H.H
Class B uses the first 16 bits for the network identifier
 The address range is from 128 - 191. The difference is = 64. The
binary equivalent to that is 00111110.00000000 The first two MSB are
0 so we use only the last 14 bits
 Number of networks that can be created = 214 = 16384
 Number of hosts per Class A network
 32 bits – 16 bits = 16 bits
 216 = 65,536 – 2 = 65,534
 Class B Structure: N.N.H.H
What would be Class C?
Exercise
Classify the following IP addresses as A,
B, or C and label the network and host
parts of the IP address:





99.1.1.0
156.1.149.9
171.13.5.233
127.1.1.255
193.4.14.1
IP Planning
What is Subnetting?

Process of subdividing a single class of network into multiple, smaller
networks.
Why do we need it?

Organization, control, and ease of management
Who does it?

The Network Administrator of the organization
How is subnetting done?

Borrow bits from the host section and move them to the “subnet” section
How many bits should I borrow?
Depends on how many subnets you want to create

What are some of the problems associated with
subnetting?
Loosing IP’s

The outside world does not have any knowledge of
our Subnetting plan

IP Planning
What is a Subnetmask?
 Special 32-bit number that, when combined (Logically
Anded) with a device’s IP address, determines which
subnetwork that particular device belongs to
For an external host to communicate with 166.144.63.12, the
router will need to interpret the subnetmask information
IP Planning
How is it written?
 All bits under the network and subnetwork sections are turned on
(1’s).
What is default subnetmask?
 The subnet mask that will be used if you do not specify one in
your TCP/IP Configuration
 255.0.0.0 for Class A
 255.255.0.0 for Class B
 255.255.255.0 for Class C
What is the relation between Subnet Mask and Bit
Mask?


Subnet mask is the dotted decimal notation of the number
of network and subnetwork bits
Bit Mask is the count of the number of network and subnet
bits
 Default bit mask for class A is 8
 Default bit mask for class B is 16
 Default bit mask for class C is 24
IP Planning
What are the rules?
 Number of subnets created =
(Number of bits borrowed from the host
2^
section)



Number of subnets Available =
2 ^ (Number of bits borrowed from the host
section) – 2
Number of hosts created per subnet
=
(Number of bits remaining under the host
2^
section)
Number of hosts available per
subnet =
2 ^ (Number of bits remaining from the host
section) – 2
Agenda
Attendance, and Review of subnetting rules
Subnetting Class C -- Case Study
Building the topology and Interconnecting
Networking Devices Using real Cisco routers and
switches
Gateways – What are they???
Packet Tracer– A quick introduction, and simulating
how a packet traverses a simple WAN (How a packet
goes from one LAN to another through routers)
Subnetting Class C– Group Exercise
Logical And
Example
Say you are assigned a Class C network
number of 200.133.175.0 (apologies to
anyone who may actually own this domain
address:). You want to utilize this network
across multiple small groups within an
organization. You can do this by subnetting
that network. Break this network into 8
subnets of 32 IP addresses each.


How many subnets can be used?
How many nodes can be in each subnet?
Building the Topology
Now, we will use real Cisco routers and switches to
connect two LANs (Let’s say, the HR department LAN
and the IT department LAN)
During this lab make sure that you take the time to
do the following:




Check the different types of interfaces that a router can
have
Know what each type of an interface is used for
Know what type of cable is used with each interface
Ask Questions
Default Gateway
The role of Routers in connecting subnets
What is a Gateway?
 Combination of software and hardware that enable two
different network segments to exchange data
 Examples: Cisco Routers, Linksys routes, Linux servers with
multiple NICs and routing services installed, windows 2000
server with multiple NICs and RRAS installed.
 The IP address of a router’s port through which a network is
connected to the router
 Every device has to have a default gateway to
communicate with other devices outside its network
Rules
1. Each router’s interface has to be on a separate network ( You can’t have two different
interfaces on the same network)
2. Each interface on the router has to be assigned an ip address and a subnet mask
3. Routers’ interfaces usually take the first available IP address on a network
4. Switches are layer 2 devices and do not need an IP address to work
5. Each PC on the network must be configured with the correct IP properties. Your PC will need
an IP address and a subnet mask to be able to communicate with other hosts on the same
network. Your PC will need a default gateway to be able to communicate with other hosts on a
different network
6. PCs and their Default Gateway must belong to the same network.
iMac
iMac
iMac
iMac
iMac
iMac
iMac
iMac
Building The Topology with
Packet Tracer
Interconnect Devices
Simulate how a Packet traverses a
simple WAN
Group Exercise
Do number 2 from the IP
Addressing/Subnet Masking
Problems
Agenda
Attendance and questions from last week’s
meeting
Group discussion about the homework
Exercise
Logical AND and group exercise
Case 1, and 2 (To be studied at home)
Sockets, well-known port numbers, DNS,
BOOTP, DHCP, and WINS
Tools: netstat, nbtstat, snlookup, and tracero
Logical And – Why
Why: The logical AND function is used
to extract the subnet ID from a host IP
address and its subnet Mask

Question: With out using the table from
the previous group exercise, can you tell to
which subnet the host 200.133.175.199
belongs???
Logical And – How
Host IP Address (in binary format)
AND
Subnet Mask (in binary format)
= Subnet ID
1 And 1 = 1
1 And 0 = 0
0 And 0 = 0
0 and 1 = 0
Short cut: X And 255 = X
X And 0 = 0
Logical AND Exercise
Given the IP Address: 199.10.10.110/248






What is the subnet mask?
How many bits were borrowed?
How many subnets were created
What is the number of theoretical hosts per
subnet?
Using the Logical And function, find the subnet ID
where the host resides
What is the broadcast address for this subnet?
Case 1
1.
Suppose you are given the IP
address 195.5.5.0 and wish
to connect Springfield and
Bedrock to Southpark. Create
an IP addressing scheme that
will meet the following
requirements:

A: Each subnet must
support between 25 and
30 devices.

B: You must have enough
subnets to address each
network.
i.
What is the subnet mask for this network?
ii.
What is the broadcast address of the 3rd subnet?
iii.
On the diagram, assign a subnet address to each network and give each
router interface an appropriate IP address for that network.
List of networks
Case 1 Answer
for the 195.5.5.0 network with the subnet mask 255.255.255.224
192.5.5.33/27
Hosts
Network
from
195.5.5.0
195.5.5.1
192.5.5.65/27
Southpark
Broadcast Address
to
195.5.5.30 195.5.5.31
195.5.5.32 195.5.5.33 195.5.5.62 195.5.5.63
192.5.5.34/27
192.5.5.66/27
195.5.5.64 195.5.5.65 195.5.5.94 195.5.5.95
195.5.5.96 195.5.5.97 195.5.5.126 195.5.5.127
195.5.5.128 195.5.5.129 195.5.5.158 195.5.5.159
Springfield
192.5.5.97/27
Bedrock
192.5.5.129/27
195.5.5.160 195.5.5.161 195.5.5.190 195.5.5.191
195.5.5.192 195.5.5.193 195.5.5.222 195.5.5.223
195.5.5.224 195.5.5.225 195.5.5.254 195.5.5.255
-
IP:192.5.5.98/27
SM: 255.255.255.224
GW: 192.5.5.97
IP:192.5.5.130/27
SM: 255.255.255.224
GW: 192.5.5.129
Rules
1. Each router’s interface has to be on a separate network ( You can’t have two different
interfaces on the same network)
2. Each interface on the router has to be assigned an ip address and a subnet mask
3. Routers’ interfaces usually take the first available IP address on a network
4. Switches are layer 2 devices and do not need an IP address to work
5. Each PC on the network must be configured with the correct IP properties. Your PC will net
an IP address and a subnet mask to be able to communicate with other hosts on the same
network. Your PC will net a default gateway to be able to communicate with other hosts on a
different network
6. PCs and their Default Gateway must belong to the same network.
Case 2
a.
b.
c.
d.
e.
Given the IP address 199.199.199.172 with a subnet mask of
255.255.255.192. Answer the following:
How many bits were borrowed?
How many subnets have been created?
How many host address per subnet?
What is the subnet address of the network containing the
given IP address?
What is the broadcast address of the network containing the
given IP address?
Case 2 Answer
List of networks
for the 199.199.199.0 network with the subnet mask 255.255.255.192
Hosts
Network
from
199.199.199.0
199.199.199.1
Broadcast Address
to
199.199.199.62 199.199.199.63
199.199.199.64 199.199.199.65 199.199.199.126 199.199.199.127
199.199.199.128 199.199.199.129 199.199.199.190 199.199.199.191
199.199.199.192 199.199.199.193 199.199.199.254 199.199.199.255
A: 2
B: 4
C: 64
D: 199.199.199.128
E: 199.199.1299.191
Sockets and Ports
Socket
 Logical address
assigned to a
specific process
running on a
computer
Sockets and Ports
Virtual circuit for the Telnet service
Host Names and Domain Name System (DNS)
Host name
 Symbolic name that describes a TCP/IP device
Domain
 Group of computers that belong to the same organization
and have part of their IP addresses in common
Domain name
 Symbolic name that identifies an organization
 Must be registered with the Internet Naming Authority.
 Must be available (not already taken by another
organization)
Domain Names
Fully qualified domain name (FQDN)
 Name of a host that includes the full domain name as well
as the host name
 Example: You work at the library of congress and named
your machine PeggySue. Your fully qualified hostname is
PeggySue.loc.gov
Top-level domains (TLDs)
 Highest-level category used to distinguish domain names
 A certain suffix that applies to an organization according to
the nature of business it conducts.
Domain Names
Domain naming conventions
What other domains are now available?
Host Files
Text file that associates TCP/IP host names with IP addresses
(was used when we had 1000 hosts on the web)
Alias
 Nickname for a node’s host name
Example: host file
This file is called lmhosts in Windows and /etc/hosts
on a UNIX-based computer
Domain Name System (DNS)
Database that is distributed over several key computers across the
Internet.
Hierarchical way of tracking domain names and their addresses, devised
in the mid-1980s
Example: How does the DNS request is processed?

From Local, Regional, National To National, Regional, Organizational
(local)
DNS server hierarchy by geography
Domain Name System (DNS)
Resolvers
 Hosts on the Internet that need to look up domain name
information
 Example, type the command telnet support.novell.com
and your Telnet client software will kick off the resolver
service to find the IP address for support.novell.com
Name servers are servers that contain databases of names
and their associated IP addresses
 Each name server manages a group of devices, collectively
known as a zone
Configuring DNS
To view or change the name
server information on a
Windows 2000PC



Right-click My Network
Places, then right-click
appropriate Network Adapter.
Select Properties, Select
TCP/IP, Select Properties.
In the TCP/IP Properties box,
click the DNS tab.
DNS Configuration properties tab
DNS Name Space
Name space
 Database of Internet IP addresses and their associated
names distributed over DNS name servers worldwide (every
name server holds a piece of that database)
 Root server
 DNS server maintained by InterNIC and acts as the
ultimate authority on how to contact the top-level
domains (how to get from .edu to .com)
 Resource record
 One record for each host
 Element of a DNS database stored on a name server that
contains information about TCP/IP host names and their
addresses
Bootstrap Protocol (BOOTP)
Service that simplifies IP address management.
Requires network administrators to enter every IP and MAC
address into the BOOTP table
• This situation is ideal for Diskless workstations:
workstations that do not contain any hard disks
Dynamic Host Configuration Protocol
(DHCP)
Automated means of assigning a unique IP address to every
device on a network
Reasons for implementing DHCP
 Reduce the time and planning spent on IP address
management
 Reduce the potential for errors in assigning IP addresses
 Enable users to move their workstations and printers without
having to change their TCP/IP configuration
 Make IP addressing transparent for mobile users
DHCP Leasing Process
Lease
 Agreement between DHCP server and client on how long
the client will borrow a DHCP-assigned address
NetBIOS Names Defined
Each Windows-based host receives a NetBIOS name during the
installation of the operating system. This name is used to uniquely
identify the machine on the network
However the NetBIOS name is not used itself to identify a host: it is
used by NetBIOS applications and processes to establish communication
with other NetBIOS applications on remote hosts
A NetBIOS name consists of 15 alphanumeric characters
If a NetBIOS name does not contain 15 characters to fill the name out
to the required 15 characters, Windows will add the necessary number
of null characters to fill the name out to the required 15 characters
A sixteenth character , which is not usually visible, is added to each
NetBIOS name to indicate the type of name, service, or group that the
NetBIOS name represents
Registration, Discovery and Release of NetBIOS
Names
Process
Broadcast
WINS
Registration
(defending a
NetBIOS
name)
Sent to every machine within
the same LAN (subnet) to
see if any machine is already
using the name being
requested
No broadcast. The name
registration request is sent
directly to WINS to see if
the requested name is
available.
Discovery
A broadcast will be sent to all
hosts to request the IP
associated with the NetBIOS
name. When obtained
results will be registered in
cache.
No Broadcast. Request is
sent directly to WINS,
which can resolve names
of hosts on the entire
Network (different
subnets)
Release
During proper shutdown,
Release request is sent
NetBIOS host sends a
directly to WINS
broadcast to release its name
LMHOSTS File
Standard Text file used to resolve NetBIOS names to IP
addresses.
The LMHOSTS file should be located in:
%systemroot%\system32\drivers\etc directory
Example:
192.168.0.1 BONGO #PRE # DOM: Resource
The LMHOSTS file is read from top to bottom. So would the
order of entries matter???

NetBIOS Node Types
B-Node: relies completely on broadcast for name registration,
discovery and release. Creates great deal of traffic on the
network
 Cache, Broadcast, End
P-Node: Point-to-point communication with a WINS server for
NetBIOS name services
 Cache, WINS, End
H-Node: default configuration in windows machine
 Cache, WINS, Broadcast up to 3 requests, LMHOST if exist,
End
NetBIOS Names and Browsing The
Network Resources
How do I get to see all these network resources when I click on My
Network Places???
What is a browse List? A list of available NetBIOS network resources
for a particular network segment.
How are the lists built and who keep them?
 NetBIOS machines announce their presence at the start up then
once every 12 minutes. Those announcements will be used by the
following special hosts to built the browse lists:
 Master Browser: One per segment
 Backup Master Browser: Future Master browser
 Domain master Browser : Pulls the master browser to get a list
of the resources on this particular segment, then sends a
complete list with all the resources on the entire network to
each Master Browser
NetBIOS Switches
Windows Internet Naming Service (WINS)
Provides a means of resolving NetBIOS names with IP addresses
What are NetBIOS names?
How are DNS names different from NetBIOS?
Make sure that you can differentiate between TCP/IP host names
and NetBIOS names
Remember that NetBIOS is used primarily with Windows-based
systems
WINS offers several advantages
 Guarantees a unique NetBIOS name is used for each
computer on a network
 Support for DHCP
 Better network performance (eliminates NetBIOS broadcast)
TCP/IP Troubleshooting
Packet Internet Groper (PING)

Troubleshooting utility that
can verify TCP/IP is installed,
bound to the NIC, configured
correctly, and communicating
with the network

How does it work? It uses
ICMP to send echo request
and echo replay messages.

What is an Echo Request?
An echo request is a signal
sent out to another computer

What is an Echo Replay? An
echo reply is the other
computer’s response signal

Process of sending this signal
back and forth is known as
pinging
Netstat and Nbstat
Netstat

Displays statistics and the state of current TCP/IP
connections
Nbstat

Provides information about NetBIOS names and their
addresses
Nslookup and Traceroute
Nslookup

Allows you to look up the DNS host name of a network node
by specifying its IP address, or vice versa. Used to
troubleshoot problems related to the DNS server.
Tracert



Uses ICMP and TTL to trace the path from one networked
node to another
What is TTL? Numeric measure used to determine how
many more network hops a datagram can make. When TTL
expires a datagram returns to the source with the identity of
the destination.
How is it done? By transmitting a series of UDP to a
specified destination
Next Meeting (After Spring Break)
Take Chapter 11 Test (Read the chapter first)
Take The Midterm Exam (Make sure that you
study both case 1, and 2 before you take the
test
Download the Project and start working on it;
It is due two weeks before the final exam!
Make sure that you have the cable kit
Read Chapter 6 (Network Hardware)
Enjoy your break