Hardware9

TCP / IP# The most popular networking protocols are Transmission

Control Protocol/Internet Protocol (TCP/IP).

# TCP/IP was originally developed in the 1970s by the

Department of Defense (DOD) as a way of connecting

dissimilar networks that would be capable of withstanding

a nuclear attack.

# It is important to note that although TCP and IP are the

cornerstone protocols, TCP/IP is actually a collection of

many protocols that are generically referred to as the

TCP/IP protocol suite.

θ The two main protocols that make up the TCP/IP suite of protocols are TCP and IP.

θ These protocols fall into the Transport and Network layers of the OSI model, respectively.

θ IP functions at the Network layer of the OSI model.

θ The primary function of IP is to provide each attached device with a unique address.

θ Each address indicates not only the individual device, but also the network to which the device belongs.

θ The IP protocol is also responsible for routing packets over an internet work.

TCP / IP

θ The IP address is used to determine the exact location of the destination network where the device exists.

θ TCP is a Transport layer protocol whose primary function is to provide reliable delivery of data through a connection oriented service.

Sending data through TCP is a two-part process

The sender and receiver exchange a ‘handshake’ to establish communication, and then acknowledgements are sent to verify that data was received. Acknowledgements are being sent throughout the transmission.

TCP / IP

Benefits of TCP/IP:

TCP/IP is commonly used as the Transport and Network

layer protocol for these reasons:

1. It support almost all network operating systems.

It is the required protocol for communicating over

the Internet. if you want to connect to the Internet

your computer has to use TCP/IP.

2. The protocol is designed to be fault tolerant and is

able to dynamically reroute packets if network links

become unavailable (assuming alternate paths exist).

TCP / IP

Benefits of TCP/IP:

3. Protocol companions such as Dynamic Host

Configuration Protocol (DHCP) simplify IP

address management.

4. Domain Name System (DNS) is used with TCP/IP

to resolve a fully qualified domain name (FQDN),

such as sybex.com with its corresponding IP address.

5. TCP/IP is scalable to small and large networks.

TCP / IP

Disadvantages of TCP/IP

Although TCP/IP and the Internet have been wildly

successful, using this protocol has disadvantages.

1. Managing IP addresses is complicated and

cumbersome. IP address errors are usually

due to administrative error.

2. Troubleshooting TCP/IP problems on your

network requires an understanding of how

TCP/IP works and of the more than a dozen

protocols that are included in the suite.

TCP / IP

Disadvantages of TCP/IP

3. Taking advantage of some of the best features

of the TCP/IP suite requires considerable skill

and knowledge.

Depending on your type of business, mastering

TCP/IP will require a significant amount of

education for you or necessitate the hiring of an

expert.

TCP / IP

TCP / IPIP ADDRESSING

# Ipv4 only uses 32-bit (4-byte) addresses, which limits the address space to 4,294,967,296 (232) possible unique addresses.

# Many IP address are reserved for special purposes such as private networks (~18 million addresses) and multicast addresses (~270 million addresses).

# This reduces the number of addresses that can be allocated as public Internet addresses, and as the number of addresses available is consumed, an IPv4 address shortage appears. This limitation has helped stimulate the push towards IPv6.

TCP / IP#I Pv4 addresses are usually represented in dotted-decimal

notation (four numbers, each ranging from 0 to 255, separat

by dots, e.g. 147.132.42.18).

# Each range from 0 to 255 can be represented by 8 bits, and is

therefore called an octet. It is possible, although less common,

to write IPv4 addresses in binary or hexadecimal.

# When converting, each octet is treated as a separate number.

(So 255.255.0.0 in dot-decimal would be FF.FF.00.00 in hexa

decimal.)

TCP / IP# Currently, three classes of networks are commonly used.

i) Class A

ii) Class B

iii) Class C

# These classes may be segregated by the number of octets used to identify a single network, and also by the range of numbers used by the first octet.

# Class A networks (the largest) are identified by the first octet, which ranges from 0 to 127. Within the class A networks, the 0 network is reserved by IANA and 127 is reserved for the loopback network.

TCP / IP

ClasClasss

Range Range of first of first octetoctet

NetworNetwork IDk ID

Host Host IDID

Possible Possible number number

of of networknetwork

ss

Possible Possible number of number of

hostshosts

AA 0 – 1270 – 127 aa b.c.db.c.d 128 = 128 = (2(277))

16,777,214 16,777,214 = (2= (22424 - 2) - 2)

BB128 – 128 – 191191 a.ba.b c.dc.d 16,384 = 16,384 =

(2(21414))65,534 = 65,534 = (2(21616 - 2) - 2)

CC192 - 192 - 223223 a.b.ca.b.c dd

2,097,152,097,152 = (22 = (22121))

254 = (2254 = (288 - - 2)2)

# Class B networks are identified by the first two octets, the first of which ranges from 128 to 191.

# Class C networks (the smallest) are identified by the first three octets, the first of which ranges from 192 to 223.

Some first-octet values have special meanings:

First octet 127 represents the local computer, regardless of what network it is really in. This is useful when testing internal operations.

First octet 224 and above are reserved for special purposes such as multicasting.

Octets 0 and 255 are not acceptable values in some situations, but 0 can be used as the second and/or third octet (e.g. 10.2.0. 100).

TCP / IP

TCP / IPIPV4 PRIVATE ADDRESSES

# A large company is assigned a class A network, and segregates it further into smaller sub-nets using Classless Inter-Domain Routing.

# Machines not connected to the outside world (e.g. factory machines that communicate with each other via TCP/IP) need not have globally-unique IP addresses. # Three ranges of IPv4 addresses for private networks, one per class, were standardized by RFC 1918; these addresses will not be routed, and thus need not be coordinated with any IP address registrars.

TCP / IP

IANA Reserved Private IANA Reserved Private Network RangesNetwork Ranges

Start of Start of rangerange

End of End of rangerange

The 24-bit BlockThe 24-bit Block 10.0.0.010.0.0.0 10.255.255.10.255.255.255255

The 20-bit BlockThe 20-bit Block 172.16.0.172.16.0.00

172.31.255.172.31.255.255255

The 16-bit BlockThe 16-bit Block 192.168.0192.168.0.0.0

192.168.25192.168.255.2555.255

TCP / IP Currently, only Class C addresses are available. The supply

of IP addresses has dwindled to the point that all addresses are almost allocated.

A new IP addressing scheme with 6 octets, 48 bits is in the works. “Known as IPv6, this standard will supply billions of new IP addresses.

When you configure a network device with TCP/IP, you typically need three pieces of information:

i ) IP addressii) Subnet maskiii) Default gateway

TCP / IP

IP ADDRESS

Each network device needs a unique IP address. The system

administrator, or someone who coordinates IP address

assignment and configuration, should assign this address

from the pool of addresses assigned by Inter-NIC or your ISP.

TCP / IP

SUBNET MASK

A subnet mask defines which part of the IP address is the

network address and which is the host address. By defining

subnet masks, you specify which network your node belongs

to. With this information and the destination address for your

data, TCP/IP can determine whether source and destination

nodes are on the same network segment. If they are on

different segments, routing will be needed.

TCP / IPDEFAULT ROUTER OR GATEWAY

You need a default router, or gateway, configured on your workstations if you want your packets routed over an internet-work.

The default router is the IP address of the local router that you use to connect your network to the internet.

The workstation needs to have this information if it wants to send packets out to the Internet. Without it, the workstation is clueless about where to send packets destined for external networks.

TCP/IP REFERENCE MODEL

TCP/IP reference model originates from the grandparent of all computer networks, the ARPANET and now is used in its successor, the worldwide Internet.

The name TCP/IP of the reference model is derived from two primary protocols of the corresponding network architecture.

INTERNET LAYER

Θ The internet layer is the linchpin of the whole architecture.

Θ It is a connectionless internetwork layer forming a base for

a packet-switching network.

Θ Its job is to permit hosts to inject packets into any network

and have them travel independently to the destination. It

works in analogy with the (snail) mail system.


THE INTERNET LAYER

Θ The internet layer defines an official packet format and

protocol called IP (Internet Protocol).

Θ The job of the internet layer is to deliver IP packets where

they are supposed to go.

Θ TCP/IP internet layer is very similar in functionality to the

OSI network layer.


TRANSPORT LAYER

The layer above the internet layer in the TCP/IP model is now usually called transport layer.

It is designed to allow peer entities on the source and destination hosts to carry on a conversation, the same as in the OSI transport layer.

Two end-to-end protocols have been defined here:


APPLICATION LAYER

The application layer is on the top of the transport layer. It contains all the higher level protocols. Some of them are:

Virtual terminal (TELNET) - allows a user on one machine to log into a distant machine and work there.

File transfer protocol (FTP) - provides a way to move data efficiently from one machine to another.

Electronic mail (SMTP) - specialized protocol for electronic mail.

Domain name service (DNS) - for mapping host names onto their network addresses.


HOST-TO-NETWORK LAYER

Bellow the internet layer there is a great void. The TCP/IP reference model does not really say much about what happens here, except to point out that the host has to connect to the network using some protocol so it can send IP packet over it. This protocol is not defined and varies from host to host and network to network.


TCP/IP PROTOCOLS

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