TCP/IP:What is it ?

TCP/IP

After study this section, we would be Families with following question.

• What is TCP/IP model ?
• How it is differ form OSI model ?
• How does the DOD model Relate whth osi model ?
• What is the role of the subnet mask?
• What is the default address class of the IP address?
• What three address ranges are used for private IP addresses?
• What is the broadcast address of network?

Introduction in steps:

• The Internet protocol suite is the conceptual model and set of communications protocols used in the Internet and similar computer networks. 
• During its development, versions of it were known as the Department of Defense (DoD) model because the development of the networking method was funded by the United States Department of Defense with the help of DARPA.
• It is commonly known as TCP/IP because the fundamental units in suite are the Transmission Control Protocol (TCP) and the Internet Protocol.
• The Internet protocol suite provides end-to-end data communication specifying how data should be :

• Packetized, 
• Addressed, 
• Transmitted, 
• Routed, and 
• Received. 
• This functionality is organized into four   layers, which classify all related protocols according to the scope of networking  
• From lowest to highest, the layers are linked, and  containing communication methods for data that remains within a single network segment (link);
• The internet layer, providing inter-networking between independent networks; 
• The transport layer, handling host-to-host communication; and 
• Application layer, providing process-to-process data exchange for applications.

The technical standards underlying the Internet protocol suite and its constituent protocols are maintained by the Internet Engineering Task Force (IETF).

TCP/IP Protocol Suite Facts

What is Protocol Suites ?

• Groups of protocols are called protocol suites or protocol stacks which are  designed to interact and be used together. Nearly all computers today uses TCP/IP protocols for communication because it is highly salable. When learning about TCP/IP protocols, it is common to use a theoretical layered model called as  TCP/IP model which is also known as the Department of Defense (DoD) model.

The layers of the DoD model are as follows:

1.The Application layer :- 

• It is also called the Process layer)
•  corresponds to the Session,Presentation, and Application layers of the OSI model.

2. The Host-to-host layer :-

• it is similar to the Transport layer of the OSI model
• it is responsible for error checking and reliable packet delivery. 
• In this layer the data stream is broken into segments that must be assigned sequence numbers so that the segments can be reassembled correctly on the remote side after they are transported.

3. The Internet layer :-

• It is similar to the Network layer of the OSI model. 
• It is responsible for moving packets through a network. 
• This involves addressing of hosts and making routing decisions to identify how the packet transverses the network.

4. The Network Access layer :-

• This layer corresponds to the  Physical and Data Link layers of the OSI model. 
• It is responsible for describing the physical layout of the network and how messages are formatted on the transmission medium. Sometimes this layer is divided into the Network Access and the Physical layer.

Port No.	Protocol	Description
	TCP	Transmission Control Protocol (TCP) operates at the Transport layer. It provides connection-oriented services and performs segment sequencing and service addressing. It also performs important error-checking functions and is considered a host-to-host protocol.
	UDP	It also performs functions at the Transport layer. However, User Datagram Protocol (UDP) is considered a host-to-host protocol like TCP. it is not connection-oriented like TCP. Because of less overhead, it transfers data faster, but is not as reliable.
	IP	Internet Protocol (IP) is the main TCP/IP protocol. It handles logical addressing issues through the use of IP addresses. On the basis of  information,  received from ARP, It makes decisions to forward the packets .
	ARP	Address Resolution Protocol (ARP) is used to get the MAC address of a host from a known IP address. ARP is used within a subnet to get the MAC address of a device on the same subnet .
	RARP	RARP (Reverse Address Resolution Protocol) are used to discover the IP address of a device with a known MAC address.
	OSPF	Open Shortest Path First (OSPF) is a packet routing protocol which discover route that uses the link-state method to send the packet for source to destination. It is more efficient than RIP in updating routing tables, especially on large networks.
	RIP	Routing Information Protocol (RIP) is also a route discovery protocol that uses the distance-vector method to descover the route to forward the packets. If the network is large and complex , OSPF should be used instead of RIP.
	EIGRP	Enhanced interior gateway routing protocol is the enhanced version of ospf and rip and is covering the key feature of distance vector routing protocols and link state protocols like RIP & OSPF, so it is also called as hybrid protocols
20/21	FTP	File Transfer Protocol (FTP) is a generic method of transferring files. It  can include file security through usernames and passwords,  and it allows file transfer between dissimilar computer systems.
67/68	DHCP	The Dynamic Host Configuration Protocol (DHCP) manage the  address administration. DHCP is used on networks that do not use static IP address assignment (almost all of them). A DHCP server can be set up by an administrator or engineer with a pool of addresses that are available for assignment. When a client device is turned on it can request an IP address from the local DHCP server. This assignment is not permanent and expires at a configurable interval. DHCP has the following two components. ·         A protocol for delivering IP configuration parameters from a DHCP server to a host ·         A protocol specifying how IP addresses are assigned
161/162	SNMT	Simple Network Management Protocol (SNMP) is a protocol designed for managing complex networks. SNMP lets network hosts exchange configuration and status information.
5060/5004	(VoIP)	. (VoIP) Voice over IP is a protocol  to  carry telephony signals as digital audio encapsulated in a data packet stream over IP. It is optimized for the transmission of voice through the Internet or other packet switched networks. . Port 5060 is used for both TCP and UDP transmissions. It is the gateway for VoIP communications  including  phone transmissions,  streaming media, instant messaging, gaming and online conferencing.  . Port 5004 UDP is most often used for transmission of data packets within a computer network.
22	SSH	SSH is the primary method used to manage network devices securely at the command level. It is typically used as a secure alternative to Telnet which does not support secure connections.
23	TELNET	Remote Terminal Emulation (Telnet) allows an attached computer to act as a dumb terminal, with the help of TCP/IP host computer. It is also widely used to provide connectivity between dissimilar systems.
25	SMTP	Simple Mail Transfer Protocol (SMTP) is used to route electronic mail through the internetwork. E-mail applications provide the interface to communicate with SMTP or mail servers.
53	DNS	Domain Name System (DNS) is a system that is distributed throughout the internetwork to provide address/name resolution. For example, the name "www.testout.com" would be identified with a specific IP address.
69	TFTP	Trivial File Transfer Protocol (TFTP) is similar to FTP. It lets you transfer files between a host and an FTP server. However, it provides no userauthentication and uses UDP instead of TCP as the transport protocol.
80	HTTP	The Hypertext Transfer Protocol (HTTP) is used by Web browsers and Web servers to exchange files (such as Web pages) through the World Wide Web and intranets. HTTP can be described as an information requesting and responding protocol. It is typically used to request and send Web documents, but is also used as the protocol for communication between agents using different TCP/IP protocols.
179	BGP	BGP version 4 is widely used on the public internet and by Internet Service Providers (ISP) to maintain very large routing tables and traffic processing. BGP is one of the few protocols that have been designed to deal with the astronomically large routing tables that must exist on the public Internet. This is the most complicated and the only exterior gateway routing protocol being used today’s. network .
443	HTTPS	HTTPS is used in conjunction with HTTP to provide the same services but doing it using a secure connection which is provided by either SSL or TLS.

What do you mean by port no? why we uses it. ?

If I says, please go to market and buy something, you will  visit the  whole market but couldn’t  buy anything because you don’t  know what to buy, but if I say  buy me  a wireless modem, then instead of  visiting  the whole, you will visit the electronic market with specific  shop having networking equipment and will buy for me. Similarly the  port number identifies the particular service to be delivered or say is a way to identify a specific process to which an Internet or other network message is to be forwarded when it arrives at a server, i.e Port is address of the service within the System. For  the TCP and UDP Protocol, a port number is a 16-bit integer that is put in the header appended to a message unit.

What is port number in IP address?

So IP address + Port defines address of the particular service on the particular system. Port number is used to identify an application/services which you want to talk to on your system. Some predefined ports like 80 = HTTP server, 23 = Telnet

Which port no is used by ARP?

ARP requests are not sent using ports, they are broadcast traffic and it could not work else way, since ARP traffic is used by IP protocol to find out relationship between MAC address (data link layer) and IP address (network layer), not TCP/UDP (which is transport layer).

What is ARP and why is it used?

ARP - Address Resolution Protocol Short for Address Resolution Protocol, a network layer protocol used to convert an IP address into a physical address (called a DLC address), such as an Ethernet address. ... There is also Reverse ARP (RARP) which can be used by a host to discover its IP address.

IP Addressing

What is ip address ?

An Internet Protocol address (IP address) is a numerical label assigned to each device connected together. IP addresses allow hosts to participate on IP based networks.  An IP address serves two main functions: host or network interface identification and location addressing. They are of two type

IPv4 and IPv6

IPv4:-

•  It is a 32 bit binary number represented as four octets (four 8-bit values).
•  Each octet is separated by a period.
•  There are three types of IPv4 addresses:

o   Network address, i.e  ...192.168.1.0

o    Host address, i.e …….192.168.1.1 to 192.168.1.254 and

o   Broadcast address……192.168.1.255

• IP addresses can be represented in one of two ways:
• Decimal:-. In decimal notation, each octet must be between 0 and 255, i.e  192.168.1.1
• Binary :-In binary notation, each octet is an 8-digit number.

(for example 10000011.01101011.00000010.11001000)

                           8 bit...…8  bit……8 bit………8 bit

• The IP address includes both the network and the host address.
• The subnet mask is a 32-bit number that is associated with each IP address which play master roll in  identifying the network portion/batch of the address. In binary form, the subnet mask is always a series of 1's followed by a series of 0's (1's and 0's are never mixed mask might be decimal -255.255.255.0 Binary  - 11111111.11111111.11111111.00000000)

In later section we will learn in detail about IPv4 and IPv6

  

Now the big question arise in your mind is that ,

What is Network address?

Host address?

What is broadcast address?

Network Address – while talking about the network address the only thing to have  in mind is that 

• It is  The portion of  address which we referred as  network is
• Uses the first address in the network batch,
• The network address is reserved and is not usable by a host
• All hosts in a network batch will have the same network address or say
• All hosts in a network will have the same network bits or network portion/batch 

Broadcast Address – For a given network batch/ portion broadcast address is

·         used to send data to all of the hosts/user on a network

·         Uses the highest (last) address in the network,

·         The broadcast address is reserved and is not usable by a host

·         The bits in host portion are all 1’s

·         Also called a directed broadcast.

Host Address – these are The addresses

•  Assigned to the end devices in the network
•  Each and every device in the network needs a unique ip address,
• The host addresses lie between the network and broadcast address

There are some default classless of ip address based on there subnet mask which could be classified as:-

Class	Range of address	Default Mask	No. of Network	No. of Usable hosts/Network
Class A	1.0.0.0  to 126.255.255.255	255.0.0.0	126	2^24-2=16777216
Class B	128.0.0.0 to 191.255.255.255	255.255.0.0	2^14=65384	2^16-2=65534
Class C	192.0.0.0 to 223.255.255.255	255.255.255.0	2^21=2097152	2^8-2  =254
Class D	224.0.0.0 to 239.255.255.255	NA		Reserve for Multicast
Class E	240.0.0.0 to 255.255.255.255	NA		Reserved for experimental use.

Addresses in the 127.0.0.0 (127.0.0.0 to 127.255.255.255) range are reserved for the local host (in other words "this" host or the host you're currently working at). The most commonly-used address is 127.0.0.1 which is the loopback address.

Privet ip address :-The following address ranges have been reserved for private use:

• 10.0.0.0 to 10.255.255.255
• 172.16.0.0 to 172.31.255.255
• 192.168.0.0 to 192.168.255.255

These range of ip address are not routable on internet. Routers connected to the Internet typically filter messages within these ranges and prevent them from being propagated to the Internet.

Basically the privet ip address are used at local network by any organization and the same address at the same time can be used by another organization. Since these address are not routable at internet so for sending information on internet with these addresses NAT is used , using NAT-PAT , a single public ip is needed to to translate any range of privet address.

You may be Interested in:-

|             STP             |    Switch Working    |     switch Function    |        Voice Vlan         |  

|        Native VLAN    |             VLAN             |              EIA/TIA          |    Network Types        |

|       IEEE 802.11      |          IEEE 802          |              IEEE              |           IP address        |

|          TCP/IP           |   OSI Model- Layer    |            OSI Model        | Networking concepts |