TCP/IP Addressing & SubnettingUnit 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 conversion1 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 Page 10-8

Discussing IP addressing

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.

DHCPDynamic Host Configuration Protocol

Five slides from another Power Point …

Introducing DHCP

Rick Graziani graziani@cabrillo.edu 31

DHCP clients listen on UDP port 67. DHCP servers listen on UDP port 68

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 graziani@cabrillo.edu 32

Major DHCP features

Rick Graziani graziani@cabrillo.edu 33

DHCP Operation

Rick Graziani graziani@cabrillo.edu 34

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.

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 page 10-25

Configuring TCP/IP

Unit summary

• Discussed TCP/IP Addressing• Discussed subnetting and special addressing• Discussed the configuration of TCP/IP