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TCP/IP Suite: Layered Structure and Key Protocols

Explore the layered structure of the TCP/IP model and its key protocols for data communication over the internet. Learn about TCP, IP, ARP, RARP, and more.

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TCP/IP Suite: Layered Structure and Key Protocols

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  1. Chapter 5 TCP/IP Suite Visit to more Learning Resources

  2. Layered structure of TCP/IP model(TCP/IP Reference Model) --Transmission control protocol and internet protocol. --Protocols are set of rules which govern every possible communication over the internet. These protocols describe the movement of data between the host computers or internet. These offer simple naming and addressing schemes.

  3. TCP/IP was developed by Department of Defense’s Project Research Agency (ARPA, later DARPA) under the project of network interconnection. --Originally it was created to connect military networks together, later it was used by government agencies and universities.. Most widely used protocol for interconnecting computers and it is the protocol of the internet. Layer 1: Host-to-network Layer--1. Protocol is used to connect the host, so that the packets can be sent over it. 2. Varies host to host and network to network. Layer 2: Internet layer--1. Selection of a packet switching network which is based on a connectionless internetwork layer is called internet layer. 2. It the layer which holds the whole architecture together. 3. It allows the host to insert the packets. 4. It helps the packet to travel independently to the destination. 5. Order in which packets are received is different from the way they are sent. 6. IP (internet protocol) is used in this layer.

  4. Layer 3: Transport Layer-- 1. It decides if data transmission should be on parallel path or single path. 2. Functions such as multiplexing, segmenting or splitting on the data done by layer that is transport layer. 3. Transport layer breaks the message (data) into small units so that they are handled more efficiently by the network layer. 4. Functions of the transport layer are same as the OSI model. 5. Transport layer also arrange the packets sent in sequence. Layer 4: Application Layer-- 1. Protocols used in this layer are high level protocols such as TELNET, FTP (file transfer protocol etc.)

  5. Comparison between OSI & TCP/IP Model

  6. Protocols in Host to Network Layer --Home users prefer direct communication of Internet --Serial Communication is used. --Communication between Client & ISP takes place using 2 Protocols. 1) Serial Line Internet Protocol(SLIP)- This Protocol used to connect a workstation to the internet over a dial up line using modem. --Connection Oriented Protocol --Simple & widely used --A Flag byte attached at the front & back of each packet sent. --Does not have any error detection or correction facility. --SLIP supports only IP. -- It is necessary that both sides must know other’s IP address,in advance. It not possibly assign dynamic IP address. --Does not provide any authentication. --It is not an approved internet standard

  7. 2) Point to Point Protocol(PPP)- Users are connected to the internet through a telephone line or TV cable. --Used for controlling & Managing the data transfer --Services-a)Define fame format b)Define how to link between 2 devices is to be established & How the data exchange should take place. c)Decides encapsulation of n/w layer data into data link frame. d)Defines 2 device authentication. --PPP was an improvement over SLIP

  8. Network Layer Protocols1) ARP (Address Resolution Protocol): --ARP is a protocol for mapping an Internet Protocol address (IP address) to a physical machine address that is recognized in the local network. --For example, in IP Version 4, the most common level of IP in use today, an address is 32 bits long. In an Ethernet local area network, however, addresses for attached devices are 48 bits long. (The physical machine address is also known as a Media Access Control or MAC address.) -- A table, usually called the ARP cache, is used to maintain a correlation between each MAC address and its corresponding IP address. -- ARP provides the protocol rules for making this correlation and providing address conversion in both directions. ARP Operation-

  9. 2) RARP (Reverse Address Resolution Protocol): --RARP is a protocol by which a physical machine in a local area network can request to obtain its IP address from gateway server. --A network administrator creates a table in a local area networks gateway router that maps the physical machine (or Media Access Control - MAC address) addresses to corresponding Internet Protocol addresses. -- When a new machine is set up, its RARP client program requests from the RARP server on the router to be sent its IP address. --Assuming that an entry has been set up in the router table, the RARP server will return the IP address to the machine which can store it for future use.

  10. 3) Internet Protocol(IP): --Host to Host delivery Protocol --Belong to Network Layer --Designed for Internet --Connectionless datagram protocol --Unreliable Protocol --Doesn't Provide any error Control or flow control --Can detect errors & discards the packets if corrupted --It is more reliable if combine with TCP --Each IP datagram is handled independently & each one can follow different route to destination

  11. Structure of IP Header --IP Frame header contains Routing information & Control information --Version- 4 bit define version of IP, i.e.IPv4 or IPv6 --Header Length- 4 bit long defines length of the datagram header --Differential Services(DS)-8 bit defines class of datagram for Quality of service --Total Length-16 bit define total length of IP datagram --Identification-This field is used to identify the datagram originating from source host. --Flags-Used to Control & Identify the fragments. bit 0: Reserved; must be zero, bit 1: Don't Fragment (DF), bit 2: More Fragments (MF) --Fragmentation offset-13 bit field indicate the relative position of the fragment with respect to the complete datagram.

  12. --Time to live-This field limits a datagram’s lifetime. It is specified in seconds, but time intervals less than 1 second. --Protocol- This field defines higher level protocol which uses the services of the IP layer. --Header Checksum- The 16-bit checksum field is used for error-checking of the header. --Source Address --Destination Address --Options- Options are not required for every datagram. They are used for network testing & debugging.

  13. IPV6 --Features of IPv6: • An IPv6 address consists of 16 bytes (octets) • It is 128 bits long. • IPv6 specifies hexadecimal colon notation. • Therefore, the address consists of 32 hexadecimal digits, with every four digits separated by a colon • IPv6 has a much larger address space • It gives greater flexibility in address allocation. • There are three types of addresses in IPv6: unicast, anycast, and multicast. In an IPv6 address, the variable type prefix field defines the address type or purpose.

  14. IP Addressing IP address enable computers to communicate by providing unique identifiers for the computer itself & for the n/w over which it is located. --IP address is 32 bit value that contains a n/w identifiers(net- id) & Host identifiers(host- id) --The n/w administrator need to assign IP addresses to the system on their n/w.

  15. IP Address Classes An IP address is 32-bit address that uniquely and universally defines the connection of a device (for example, a computer or a router) to the Internet IP addresses are classified into 5 classes 1) Class A 2) Class B 3) Class C 4) Class D 5) Class E Class A format: (For first byte)In the first field the first bit ‘0’ indicates that it is class A network address. The next 7 bits are used indicate network id. Rest of the 3 bytes are used to indicate host id Class A: Minimum value is 0.0.0.0 and maximum value 127.255.255.255

  16. Fig: Classes of IP Address

  17. 2) Class B format: Minimum value is 128.0.0.0 to maximum value 191.255.255.255 3) Class C format: Minimum value 192.0.0.0 to maximum value 223.255.255.255 21 bits 8 bits(4th byte) 4) Class D format: If first 4 bits are 1110 the IP address belongs to class D The IPv4 networking standard defines Class D addresses as reserved for multicast. Multicast is a mechanism for defining groups of nodes and sending IP messages to that group rather than to every node on the LAN (broadcast) or just one other node (unicast).

  18. Multicast is mainly used on research networks. As with Class E, Class D addresses should not be used by ordinary nodes on the Internet. For class D minimum value for multicast address is 224.0.0.0 and maximum multi class address is 239.255.255.255 5) Class E format: For class E minimum value for reserved address is 240.0.0.0 to 255.255.255.255

  19. --Address Mask/Default Mask- Suppose , Class C IP Address 192.15.28.16 In this 192.15.28 is Network Part, 16 is Host Part Address: 192.15.28.16 11000000.00001111.00011100.00010000 Mask: 255.255.255.0 11111111.11111111.11111111.00000000

  20. Subnetting- --Logically separated network A --A subnet short for sub network is an identifiably separate part of an organization's network. --Typically, a subnet may represent all the machines at one geographic location, in one building, or on the same local area network (LAN). -- Having an organization's network divided into subnets allows it to be connected to the Internet with a single shared network address. -- Without subnets, an organization could get multiple connections to the Internet, one for each of its physically separate subnetworks.

  21. Subnet Masking --In computing world mask is data that are used for bitwise operations --if you take the example of IP Address masking where in subnet mask of class C 255.255.255.0 will be masking first 3 digits that means first three octate can not be changed for keeping yourself the part of the same network. -- Thus here mask decides host part of an IP address & a network part of an IP address

  22. Site Address : 201.70.64.0 No. of Subnets : 2 Class : Class C Default subnet mask : 255.255.255.0 To design 2 subnets : Given IP : 201.70.64.0 Network ID : 201.70.64 Subnet 1: The bit combination is 001. Taking last octet in binary :0 0 1 0 0 0 0 0 = 32 (10) Hence the subnet address is, 201.70.64. 32 Subnet 2: The bit combination is 01 0. Taking last octet in binary :0 1 0 0 0 0 0 0 = 64(10) Hence the subnet address is, 201.70.64. 64

  23. Supernetting --A supernetwork, or supernet, is an Internet Protocol (IP) network that is formed, for routing purposes, from the combination of two or more networks (or subnets) into a larger network. --To create a supernetwork, the procedure is to be reversed. The networks are combined by creating space for a larger number of hosts. To accomplish this, we start with the default subnet mask of 255.255.255.0 and use some of the bits reserved for the Net id to identify the Host id. The following example shows we would create a new supernetwork by combining four separate subnetworks. Example: If a packet arrives at the router with the destination address 192.168.64.48, the supernet mask 255.255.252.0 is applied to the destination address. 11000000.10101000.01000000.00110000 (destination IP address) AND 11111111.11111111.11111100.00000000 (Supernet mask) Returns 11000000.10101000.01000000.00000000

  24. Transport Layer Protocols-1)UDP(User Datagram Protocols) --Simple, High speed ,Unreliable,Connectionless Protocol(Don’t need to establish a connection) -- Source port number:This field identifies the sender's port when meaningful and should be assumed to be the port to reply to if needed. If not used, then it should be zero. --Destination port number: This field identifies the receiver's port and is required.

  25. Length: A field that specifies the length in bytes of the UDP header and UDP data. The minimum length is 8 bytes because that is the length of the header. Checksum: The checksum field may be used for error-checking of the header and data. The field carries all-zeros if unused.

  26. 2) TCP(Transmission Control Protocol) --Process to Process Protocol --It is Connection Oriented Protocol --It uses Flow control & error Control Mechanism --It is reliable Protocol --TCP uses Port numbers

  27. 2) TCP Header --Fig shows Layout of TCP Segment.Every segment begins with 20 byte fixed format header. --Source Port: 16 bits, The source port number. --Destination Port: 16 bits, The destination port number. --Sequence Number: 32 bits,Identifying the current position of the first data byte in the segment within the entire byte stream --Acknowledgment Number: 32 bits,this field contains the value of the next sequence number the sender of the segment is expecting to receiver. --Data Offset(Header Length): 4 bits, Total TCP Header Length --Reserved-6 bits,Reserved for future use. --Flags-6 bits, Flags are used for different purpose like Acknowledgement(ACK),Urgent Pointer(URG)-if interpret the urgent pointer field, Reset the connection(RST), No more data from sender(FIN) etc.

  28. --Window-16 bit, Used for Flow control in the form of data transmission window size --Checksum- The checksum field may be used for error-checking of the header and data. --Urgent Pointer: 16 bits, TCP sender notify the receiver of urgent data should be processed by the receiving application --Options- Provide additional functionality, several optional parameters used between TCP sender & Receiver --Padding: vary in size,The TCP header padding is used to ensure that the TCP header ends and data begins on a 32 bit boundary.

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  30. Application Layer --Provide Different Application, Addressing, Security. --Domain Name System(DNS)- .com-Commercial Organisation .edu- educational Institute .gov- Government Organisation .mil- Military Sites .net- Network Resources or Internet Service Provider .org- Non commercial organisation --Domain country names used like .in for india, .uk, .us --SMTP(Simple Mail Transfer Protocol) is used actual mail Transfer through the message transfer agent. For more Details Contact Us

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