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TCP/IP Addressing & Subnetting
Unit objectives
• Discuss TCP/IP addressing and determine the
IP address class and default subnet mask
• Discuss subnetting and special addressing
• Discuss the installation and configuration of
TCP/IP
Topic A
• Topic A: IP addressing
• Topic B: Subnetting and special addressing
• TCP/IP installation and configuration
Addressing
• Each networked system must be identified as
unique
• This is accomplished through the machine’s
MAC address
• Each machine must also have a unique IP
address
IP Addresses
• Made up of a 32-bit address or four octet address
• The three major IP address classes
–
–
–
–
Class A
Class B
Class C
There are also Class D and Class E addresses, used for
multicasts (D) and for research (E), but these
addresses are not used by any group or. individuals
Address conversion
• An IP address is a 32-bit address, written as
four octets or bytes, separated by periods.
– For example: 195.143.67.2
• This way of representing an
IP address is also known as
“dotted decimal” notation
A sample of binary numbers
Binary-to-decimal conversion
• To convert a binary number to a decimal
number
– Determine the decimal value for each of the bits
– Add up the bit values
Binary-to-decimal conversion
11000000
11011010
10011101
00000011
Binary-to-decimal conversion

1
1
0
0
0
0
0
0
128
64
32
16
8
4
2
1
128
64
0
0
0
0
0
0
The middle row here is sometimes called a “binary tree – it runs
from right to left, increasing by doubling in each subsequent spot –
1, 2, 4, 8, and so on.
 The top row is the binary number, the middle row shows the value of
each “1” in the top row. If there is a 1 in the top row, the
corresponding value for that spot in the binary tree is brought down
to the bottom row. The bottom row is just added to give you the
decimal equivalent of the binary number. In this example, 1100 0000
= 128 + 64 = 192.
Binary-to-decimal conversion
1
1
0
1
1
0
1
0
128
64
32
16
8
4
2
1
128
64
0
16
8
0
2
0
Try this one ….
Binary-to-decimal conversion
1
0
0
1
1
1
0
1
128
64
32
16
8
4
2
1
128
0
0
16
8
4
0
1
Binary-to-decimal conversion
0
0
0
0
0
0
1
1
128
64
32
16
8
4
2
1
0
0
0
0
0
0
2
1
Decimal-to-binary conversion
• To convert decimal into binary
– Set up a table as shown
– The fourth column provides bit values
IP Addressing - (Cisco PPt)
IP Addressing - (Cisco PPt)
IP Addressing - (Cisco PPt)
IP Addressing - (Cisco PPt)
IP Addressing - (Cisco PPt)
Activity A-1
page 10-5
Discussing IP addresses and conversions
The IP address classes
• Five address classes are supported by TCP/IP:
A, B, C, D, and E
• Classes A, B, and C are assigned to the general
user community
• Class D addresses are reserved for
multicasting
• Class E addresses are reserved for
experimental purposes
IP Addressing - (Cisco PPt)
• MAC to IP address translation
• IP classes
–
–
–
–
–
–
–
–
–
Internet Assigned Numbers Authority (IANA)
American Registry of Internet Numbers (ARIN)
Internet Corporation for Assigned Names and Numbers (ICANN)
Class A
Class B
Class C
Class D
Class E
Private IP ranges
The Class A network
• The first octet defines the network portion of the
address
• The last three octets are used for subnet masking
and host addresses
• A default subnet mask of 255.0.0.0 is assigned for a
Class A network
– Subnet masks? The book does get to this later; for now,
it is another 32-bit number in 4 8-bit octet form, just
like the IP address. The mask determines which part of
the IP address represents the network, and which part
the hosts on that network.
The Class B network
• The first two octets are used for the network
address
• The last two octets are used for subnetting and
host addresses
• A default subnet mask of 255.255.0.0 is assigned
for a Class B network
• A Class B address is often used when setting up a
moderate- to large-sized network
The Class C network
• The first three octets are used for the
network address
• The last octet is used for subnetting and host
addresses
• A default mask of 255.255.255.0 is assigned
to a Class C network
IPv6
• Addresses are 128 bits
• They’re made up of eight 16-bit fields,
allowing for a total of 296 addresses
• The fields are represented by 16-bit
hexadecimal numbers
• Each field can be from 0 to FFFF (65535 in
decimal) (or 65,536 addresses)
Activity A-2
Discussing IP addressing
Page 10-8
Managing addresses
• Some potential problems in implementing
TCP/IP
– Population size
– Portability
– End users
• The (one of the) standard(s) that has emerged
to assist in managing TCP/IP addresses is
DHCP
DHCP: Dynamic Host Configuration Protocol
• An open standard that is defined within RFC 2131,
Dynamic Host Configuration Protocol
• Microsoft was the first manufacturer to
implement DHCP
• Provides an automated means of managing host
IP addresses
Other addressing methods
• BootP - an earlier attempt to centralize configuration
IP addresses. The address pool is static rather than in a
dynamic pool, as with DHCP. Other differences in the
following slides.
• Static assignment – You can assign a specific
address to a node; useful if you have a device that other
devices must find – like a server or a printer, for example.
• Self assignment (APIPA) – You get an APIPA
address when your computer can’t find a DHCP server. You
can still communicate with other PCs on your network, but
you can never get to another network, like the internet.
– The APIPA client keeps searching for a DHCP server until it
finds one.
DHCP
Dynamic Host Configuration Protocol
Five slides from another Power Point …
DHCP clients listen on UDP port 67. DHCP
servers listen on UDP port 68
Rick Graziani [email protected]
Introducing
DHCP
31
BOOTP and DHCP differences
There are two primary differences between DHCP and BOOTP:
•
•
DHCP defines mechanisms through which clients can be assigned an IP address for
a finite lease period.
– This lease period allows for reassignment of the IP address to another client
later, or for the client to get another assignment, if the client moves to
another subnet.
– Clients may also renew leases and keep the same IP address.
DHCP provides the mechanism for a client to gather other IP configuration
parameters, such as WINS and domain name.
Rick Graziani [email protected]
32
Major DHCP features
Rick Graziani [email protected]
33
DHCP Operation
Remember :
•
•
•
•
‘Dora’ -
Acronym
Note on how DHCP requests are propagated:
Routers, by default, will not forward broadcast packets.
DHCP client messages use the destination IP address of 255.255.255.255 (all Nets
Broadcast).
So DHCP clients will not be able to send requests to a DHCP server on a different subnet
unless the DHCP/BootP Relay Agent is configured on the router.
Rick Graziani [email protected]
34
Activity A-3
Page 10-11
Discussing IP addressing methods
Topic B
• Topic A: IP addressing
• Topic B: Subnetting and special addressing
• TCP/IP installation and configuration
Subnetting
• Subnets
–improve network performance and
–available bandwidth and
–reduce overall traffic levels
A sample subnet
Subnet masks
• Are used to identify the network and host
portions of the address
• The network portion identifies where the
host is located, and the host portion identifies
the device connected to that network
Creating a custom subnet mask
• A custom subnet mask tells TCP/IP to consider
some of the bits, which by default would identify
a host, as part of the network address
• When a network is divided into subnets, all
members of that subnet will have the same
network prefix
• Routers divide the networks and provide
communication between them
Subnet Addressing - (Cisco PPt)
• Default class subnet masks
– Class A subnet mask is 255.0.0.0
11111111.00000000.00000000.00000000
– Class B subnet mask is 255.255.0.0
11111111.11111111.00000000.00000000
– Class C subnet mask is 255.255.255.0
11111111.11111111.11111111.00000000
• Boolean ANDing operation
• Subnet addresses
• Broadcast addresses
Broadcast Types - (Cisco PPt)
• Flooded broadcasts
– 255.255.255.255
• Directed broadcast
– 129.30.255.255
Subdividing IP Classes - (Cisco PPt)
Subnet Masking - (Cisco PPt)
Subnet Masking - (Cisco PPt)
Subnet Masking - (Cisco PPt)
Learning To Subnet: (Cisco PPt)
Learning To Subnet - (Cisco PPt)
• Breakdown of 255.255.255.244 subnet mask
–
–
–
–
–
–
–
–
0 (binary 00000000) — unusable
32 (binary 00100000)
64 (binary 01000000)
96 (binary 01100000)
128 (binary 10000000)
160 (binary 10100000)
192 (binary 11000000)
224 (binary 11100000) — unusable
Learning To Subnet - (Cisco PPt)
Learning To Subnet - (Cisco PPt)
Subnetting Formulas - (Cisco PPt)
• 2y – 2 = # of usable subnets (where y is the
number of bits borrowed)
• 2x – 2 = # of usable hosts per subnet (where x
is the number of bits remaining in the host
field after borrowing)
Subnetting Formulas - (Cisco PPt)
Subnetting Formulas - (Cisco PPt)
CIDR - (Cisco PPt)
• Classless Inter-Domain Routing (CIDR)
• Developed to slow the exhaustion of IP
Addresses
• Provide efficient use of IP addresses and
address ranges
• Subnetting and supernetting
Activity B-1
page 10-14
Discussing subnet masks
Special addressing
• There are several special addressing structures
• These conventions are documented and used on
the Internet and are part of the Internet Protocol
Private networks
• A private network is one that will not be
connecting directly to the Internet
• The term intranet is commonly used to refer
to internetworked environments of this type
NAT
• Refers to an IP gateway’s translating “private”
network addresses into valid “public” Internet
addresses
• When a machine attempts to access the Internet,
the IP gateway, using NAT, translates between the
internal private address and the valid external /
public address for both incoming and outgoing
traffic
Activity B-2
page 10-16
Discussing special addressing and private
networks
Topic C
• Topic A: IP addressing
• Topic B: Subnetting and special addressing
• TCP/IP installation and configuration
TCP/IP configuration
• You can configure the TCP/IP protocol and
related components on a Windows Server
2003/XP computer
Guidelines for using TCP/IP
• When you have significant routing requirements
• When you need UNIX connectivity
• If you want to employ TCP/IP utilities in network
management
• In environments where TCP/IP is already in use
• In Internet/intranet environments
Local Area Connection properties
TCP/IP Properties, General tab
TCP/IP Settings, Alternate Configuration tab
Advanced TCP/IP Settings, IP Settings tab
Advanced TCP/IP Settings, DNS tab
Advanced TCP/IP Settings, WINS tab
Advanced TCP/IP Settings, Options tab
Activity C-1
Configuring TCP/IP
page 10-25
Unit summary
• Discussed TCP/IP Addressing
• Discussed subnetting and special addressing
• Discussed the configuration of TCP/IP