The TCP/IP model is before the OSI model and was developed by DOD(Department of Defence), but it is not exactly like the OSI model. OSI has 7 layers whereas TCP/IP has only Four Layers-
- Application Layer/Process
- Transport Layer/Host-to-Host
- Internet Layer
- Network Layer/Link Layer
Difference between TCP/IP and OSI Model:
- TCP is known as Transmission Control Protocol whereas OSI is known as Open System Interconnections.
- TCP consists of Four Layers whereas OSI consists of Seven layers.
- TCP is more reliable whereas OSI is less.
- TCP does not consist of strict boundaries whereas OSI consists of very strict boundaries.
- TCP has both session and physical layers in the Application layer whereas OSI has separate session, physical, and application layers.
- In TCP first Protocols are developed then models whereas in OSI first Models are developed and then Protocols.
- In the TCP model, only connection-less service is provided by the network layer whereas in the OSI model both connection-less and connection-oriented services are provided by the network layer.
1. Network Layer –
Network Layer has two layers inside it one is Data link Layer and the other is the Physical Layer of the OSI Model (You can read this topic from smartiqhub.com). As this layer provides the physical transmission of data by hardware addressing and protocols presenting.
2. Internet Layer –
Internet Layer walks the same as the function of Network Layer in the OSI model, which defines the responsible protocol for logical transmission. Protocol used by Internet Layer.
- IP – Internet Protocol has two versions one is (IPv4 and the other IPv6.) delivers packets from one host to the other host (destination host) by finding the actual IP addresses from the packet headers.
- ICMP – Internet Control Message Protocol which is encapsulated within IP datagrams also responsible for providing hosts information and network problems.
- ARP – Address Resolution Protocol which finds the host’s address from the IP addresses. ARP is of several types: Reverse ARP, Proxy ARP, Gratuitous ARP, and Inverse ARP.
3. Host-to-Host Layer/Transport Layer
This layer is similar to the transport layer of the OSI model which is responsible for end-to-end communication and error-free delivery of data and also shields the upper-layer applications from the complexities of data. There are two main protocols:
- Transmission Control Protocol (TCP) – This provides reliable and error-free communication between systems and provides sequencing and segmentation of data. The only disadvantage is that Increased overhead leads to increased costs.
- User Datagram Protocol (UDP) –It does not provide features as TCP provides and also it is not reliable transport and is very cost-effective.
4. Application Layer –
This layer is similar to the Application, Presentation, and Session Layer of the OSI model which provides node-to-node communication and also controls user-interface specifications. Protocols used in this layer are HTTP, HTTPS, FTP, TFTP, Telnet, SSH, SMTP, SNMP, NTP, DNS, DHCP, NFS, X Window, LPD.
- HTTP and HTTPS – HTTP is a Hypertext transfer protocol and HTTPS is a Hypertext transfer protocol Secure which provides SSL(Secure Socket Layer) whereas in HTTP there is no SSL which is important security for authenticating and carrying out bank transactions.
- SSH – Secure Shell (SSH) is a terminal emulations software that is similar to Telnet which is used to maintain an encrypted connection.
- NTP – Network Time Protocol(NTP) which is used to synchronize the clocks on our computer for one standard time source which is very important for authorizations, and online transactions. The Bad NTP protocol can crash the server.
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