February 05, 2020
Amitraj
TCP/IP Reference Model
-> TCP/IP means Transmission Control Protocol and Internet Protocol.
-> The TCP/IP Model is developed before than OSI Model.
-> It was designed and developed by Department of Defense (DoD) in 1960s and is based on standard protocols.
-> The layers in TCP/IP Model are different than OSI Model.
Layers in TCP/IP Model
The TCP/IP Model has four layers:-
1. Network Access Layer or Host-to-network layer
2. Internet or Network layer
3. Transport layer
4. Application layer
1. Network Access Layer
-> A network Access layer is the lowest layer of the TCP/IP model.
-> A network Access layer is the combination of the Physical layer and Data Link layer and it is combined known as Host to Network layer.
-> It defines how the data should be sent physically through the network.
-> This layer is mainly responsible for the transmission of the data between two devices on the same network.
-> The functions carried out by this layer are encapsulating the IP datagram into frames transmitted by the network and mapping of IP addresses into physical addresses.
-> The protocols used by this layer are ethernet, token ring, FDDI, X.25, frame relay.
2. Internet Layer
-> An internet layer is also known as network layer.
-> The main responsibility of the internet layer is to send the packets from any network, and they arrive at the destination irrespective of the route they take.
-> In the network layer, the TCP/IP model supports internetworking protocol in short known as IP.
Internetworking protocol(IP) -
1. It is an unreliable connectionless protocol used by TCP/IP Model.
2. This protocol is used for data transmission.
3. This protocol doesn’t do error checking or tracking of data, thus we cannot be sure that the data is actually reached its destination. This is why it is also known as best effort delivery service which means this protocol tries it best to send the data to its destination but doesn’t take an guarantee.
4. IP protocol transmits the data in form of small packets known as datagrams. Each of these datagrams are transmitted separately, thus they can take different routes and sometime duplicate datagrams can be reached to destination, also they are reached in no particular order at the destination.
ARP Protocol -
1. ARP stands for Address Resolution Protocol.
2. ARP is a network layer protocol which is used to find the physical address from the IP address.
3. The two terms are mainly associated with the ARP Protocol:
a. ARP request:- When a sender wants to know the physical address of the device, it broadcasts the ARP request to the network.
b. ARP reply:- Every device attached to the network will accept the ARP request and process the request, but only recipient recognize the IP address and sends back its physical address in the form of ARP reply. The recipient adds the physical address both to its cache memory and to the datagram header.
ICMP Protocol -
1. ICMP stands for Internet Control Message Protocol.
2. Network layer sends data in form of small packets known as datagrams. ICMP protocol sends the datagrams problems back to sender. It is used for query and error reporting messages.
3. A datagram travels from router-to-router until it reaches its destination. If a router is unable to route the data because of some unusual conditions such as disabled links, a device is on fire or network congestion, then the ICMP protocol is used to inform the sender that the datagram is undeliverable.
4. The core responsibility of the ICMP protocol is to report the problems, not correct them.
3. Transport Layer
The transport layer is responsible for the reliability, flow control, and correction of data which is being sent over the network.
Three protocols used in the transport layer are User Datagram protocol and Transmission control protocol and Stream Control Transmission Protocol.
User Datagram protocol (UDP) -
1. UDP is a process to process protocol used for data transmission.
2. It takes the data from upper layer of TCP/IP Model and adds following information to the data:
a) Port Address – Source port address of 16 bits and destination port address of 16 bits added to the data so that it reaches to correct destination and displays the correct source of data.
b) checksum error control – 16 bits of checksum data is added to the data received from upper layer, this is used for error control.
c) length of data – Length defines the total bytes of data in datagram.
3. Although this protocol finds the error in the transmission of data, it doesn’t specify the error which makes it hard to identify the actual error in transmission.
Transmission control protocol (TCP) -
1. Unlike UDP which is a connectionless protocol, the TCP is a connection oriented protocol.
2. A connection must be made between sender and receiver before the transmission of data.
3. TCP protocol divides the data in small units called segments. Each segment contains the sequence number which makes it possible to rearrange the segments in correct order at the receiver side to make the complete data.
4. It also adds acknowledgement number to the segments to verify that the data is actually reached its destination or not.
5. Unlike UDP which is unable to specify the exact error in transmission, this protocol does error control and specifies the exact error which makes TCP a reliable protocol.
Stream Control Transmission Protocol (SCTP)-
1. This protocol combines the best features of TCP and UDP protocols.
2. It was discovered later to support newer applications such as voice data transmission over the internet.
4. Application Layer
1. An application layer is the topmost layer in the TCP/IP model.
2. It is responsible for handling high-level protocols, issues of representation.
3. This layer allows the user to interact with the application.
4. When one application layer protocol wants to communicate with another application layer, it forwards its data to the transport layer.
5. There is an ambiguity occurs in the application layer. Every application cannot be placed inside the application layer except those who interact with the communication system.
Following are the main protocols used in the application layer:
1. HTTP:- HTTP stands for Hypertext transfer protocol, it allows the user to interact with world wide web through the browser application. HTTP can be used to transfer various types of data such as plain text, audio, video etc.
2. FTP:- FTP stands for File Transfer Protocol. This protocol is used for transmitting files from one system to another system.
3. TELNET:- TELNET is a client-server protocol. It is a reliable connection oriented protocol. This protocol is used on internet or on LAN to provide a bidirectional (both ways) text based communication through a virtual terminal connection.
4. DNS:- DNS stands for Domain Name System. Each computer on a network has different IP address, a computer is known by its IP address. DNS provides a mapping to a name to the IP Address so a name can be used to identify a system on network rather than IP address itself.
5. SNMP:- SNMP stands for Simple Network Management Protocol. It managers the devices connected to the internet using TCP/IP protocol.
6. SMTP:- SMTP stands for Simple mail transfer protocol. It is used for email services, using this protocol a email containing data can be sent to another email address.
-> TCP/IP means Transmission Control Protocol and Internet Protocol.
-> The TCP/IP Model is developed before than OSI Model.
-> It was designed and developed by Department of Defense (DoD) in 1960s and is based on standard protocols.
-> The layers in TCP/IP Model are different than OSI Model.
Layers in TCP/IP Model
The TCP/IP Model has four layers:-
1. Network Access Layer or Host-to-network layer
2. Internet or Network layer
3. Transport layer
4. Application layer
1. Network Access Layer
-> A network Access layer is the lowest layer of the TCP/IP model.
-> A network Access layer is the combination of the Physical layer and Data Link layer and it is combined known as Host to Network layer.
-> It defines how the data should be sent physically through the network.
-> This layer is mainly responsible for the transmission of the data between two devices on the same network.
-> The functions carried out by this layer are encapsulating the IP datagram into frames transmitted by the network and mapping of IP addresses into physical addresses.
-> The protocols used by this layer are ethernet, token ring, FDDI, X.25, frame relay.
2. Internet Layer
-> An internet layer is also known as network layer.
-> The main responsibility of the internet layer is to send the packets from any network, and they arrive at the destination irrespective of the route they take.
-> In the network layer, the TCP/IP model supports internetworking protocol in short known as IP.
Internetworking protocol(IP) -
1. It is an unreliable connectionless protocol used by TCP/IP Model.
2. This protocol is used for data transmission.
3. This protocol doesn’t do error checking or tracking of data, thus we cannot be sure that the data is actually reached its destination. This is why it is also known as best effort delivery service which means this protocol tries it best to send the data to its destination but doesn’t take an guarantee.
4. IP protocol transmits the data in form of small packets known as datagrams. Each of these datagrams are transmitted separately, thus they can take different routes and sometime duplicate datagrams can be reached to destination, also they are reached in no particular order at the destination.
ARP Protocol -
1. ARP stands for Address Resolution Protocol.
2. ARP is a network layer protocol which is used to find the physical address from the IP address.
3. The two terms are mainly associated with the ARP Protocol:
a. ARP request:- When a sender wants to know the physical address of the device, it broadcasts the ARP request to the network.
b. ARP reply:- Every device attached to the network will accept the ARP request and process the request, but only recipient recognize the IP address and sends back its physical address in the form of ARP reply. The recipient adds the physical address both to its cache memory and to the datagram header.
ICMP Protocol -
1. ICMP stands for Internet Control Message Protocol.
2. Network layer sends data in form of small packets known as datagrams. ICMP protocol sends the datagrams problems back to sender. It is used for query and error reporting messages.
3. A datagram travels from router-to-router until it reaches its destination. If a router is unable to route the data because of some unusual conditions such as disabled links, a device is on fire or network congestion, then the ICMP protocol is used to inform the sender that the datagram is undeliverable.
4. The core responsibility of the ICMP protocol is to report the problems, not correct them.
3. Transport Layer
The transport layer is responsible for the reliability, flow control, and correction of data which is being sent over the network.
Three protocols used in the transport layer are User Datagram protocol and Transmission control protocol and Stream Control Transmission Protocol.
User Datagram protocol (UDP) -
1. UDP is a process to process protocol used for data transmission.
2. It takes the data from upper layer of TCP/IP Model and adds following information to the data:
a) Port Address – Source port address of 16 bits and destination port address of 16 bits added to the data so that it reaches to correct destination and displays the correct source of data.
b) checksum error control – 16 bits of checksum data is added to the data received from upper layer, this is used for error control.
c) length of data – Length defines the total bytes of data in datagram.
3. Although this protocol finds the error in the transmission of data, it doesn’t specify the error which makes it hard to identify the actual error in transmission.
Transmission control protocol (TCP) -
1. Unlike UDP which is a connectionless protocol, the TCP is a connection oriented protocol.
2. A connection must be made between sender and receiver before the transmission of data.
3. TCP protocol divides the data in small units called segments. Each segment contains the sequence number which makes it possible to rearrange the segments in correct order at the receiver side to make the complete data.
4. It also adds acknowledgement number to the segments to verify that the data is actually reached its destination or not.
5. Unlike UDP which is unable to specify the exact error in transmission, this protocol does error control and specifies the exact error which makes TCP a reliable protocol.
Stream Control Transmission Protocol (SCTP)-
1. This protocol combines the best features of TCP and UDP protocols.
2. It was discovered later to support newer applications such as voice data transmission over the internet.
4. Application Layer
1. An application layer is the topmost layer in the TCP/IP model.
2. It is responsible for handling high-level protocols, issues of representation.
3. This layer allows the user to interact with the application.
4. When one application layer protocol wants to communicate with another application layer, it forwards its data to the transport layer.
5. There is an ambiguity occurs in the application layer. Every application cannot be placed inside the application layer except those who interact with the communication system.
Following are the main protocols used in the application layer:
1. HTTP:- HTTP stands for Hypertext transfer protocol, it allows the user to interact with world wide web through the browser application. HTTP can be used to transfer various types of data such as plain text, audio, video etc.
2. FTP:- FTP stands for File Transfer Protocol. This protocol is used for transmitting files from one system to another system.
3. TELNET:- TELNET is a client-server protocol. It is a reliable connection oriented protocol. This protocol is used on internet or on LAN to provide a bidirectional (both ways) text based communication through a virtual terminal connection.
4. DNS:- DNS stands for Domain Name System. Each computer on a network has different IP address, a computer is known by its IP address. DNS provides a mapping to a name to the IP Address so a name can be used to identify a system on network rather than IP address itself.
5. SNMP:- SNMP stands for Simple Network Management Protocol. It managers the devices connected to the internet using TCP/IP protocol.
6. SMTP:- SMTP stands for Simple mail transfer protocol. It is used for email services, using this protocol a email containing data can be sent to another email address.
