Computer Networks Architecture: The TCP/IP protocol suite

Define process, host and network with respect to TCP/IP protocol architecture.

Ans: The TCP/IP protocol suite is based on a view of communication that involves three agents: process, host and networks. Processes are the fundamental that communicate. A process executes on hosts, which can often multiple simultaneous processes. Communication between processes takes place across networks to which the hosts are attached.

What is a gate way?

 A gateway is processor connecting two networks whose primary function is to relay data between networks using an internetworks protocol.

 Name the general types of protocols seen to needed host-host layer.

 Four general types of protocols seen to be needed host-host protocol:-

1. A reliable connection-oriented data protocol.
2. A diagram protocol.
3. A speech protocol
4. A real-time data protocol

What is a subnetwork?

 The TCP and IP protocols are configured for communications. The total communications facility may consists of multiple networks, the constituent networks are usually referred to as subnetworks.

What is a port?

 For successful communication, every entity is the overall system must have a unique address. Actually, Two levels of addressing are needed. Each host on a subnetwork must have a unique global internet address; this allows to be delivered to the proper host. Each process with a host must have an address that is unique within the host; this allows the host-to-host protocol (TCP) to deliver data to the proper process. These latter addresses are known as ports.

 Briefly describe the difference between the TCP/IP protocol suite and OSI model.

 There are fundamental differences between the TCP/IP protocol suit and OSI model.

1. Hierarchies versus layering: The OSI model is layered, but TCP/IP protocol suit is modular and hierarchical and gives the designer mode to develop efficient, cost-effective and rich protocol.
2. Internetworking: Unlike the OSI model, the TCP/IP protocol suit places importance on internetworking between two different networks.
3. Connectionless service: A connectionless service in one in which data are transferred from one entity to another without the prior mutual construction of a connection (e.g. datagram). The TCP/IP protocol suit places equal importance on connectionless and connection-oriented services, whereas the OSI model couched slowly in terms of connectionless service within the TCP/IP protocol suit is in internetworking.
4. Management functions: the TCP/IP protocol suit and the OSI model differently treat the management-related functions.

 Discuss the layers of the TCP/IP protocol architecture?

 The protocol is organized into four layers:

1. Network access layer
2. Internet layer
3. Host-to-host layer
4. Process/application layer

a) Network access layer: the network access layer contains those protocols that provide access to a communication networks. Protocols at this layer are between a communications node and an attached host. A function of all these protocols id to route data between hosts attached to the same network. Other services provided are flow control and error control between hosts and various qualities of service features such as priority and security. A network layer entity is typically invoked by an entity is either the internet or host-host layer but may be invoked by a process/application layer entity.

b) The internet layer: The internet layer consists of the procedures required to allow data to traverse multiple networks between hosts. Thus it must provide a routing function. This protocol is usually implemented within hosts and gateways. A gateway is a processor connecting two networks whose primary function is to relay data between networks using a n internetwork protocol.

c)The host-host layer: The host-host layer contains protocol entities with the ability to deliver data between two processes on different host computers. A protocol entity at this level may (or may not) provide a logical connection between higher level entities. Other possible services include error and flow control and the ability to deal with control signals not associated with a logical data connection.

Four general types of protocols seen to be needed at this level:

1. A reliable connection-oriented data protocol
2. A datagram protocol
3. A speech protocol
4. A real time data protocol

1. The process/application layer: The process and application layer contains protocols for resource sharing and remote access within the TCP/IP protocol suit architecture, there are the following protocol standards:
   1. Internet Protocol (IP): Which provides a connectionless service for and systems to communicate across one or more networks and does not assure the networks to be reliable.
   2. Host-host layer: Transmission control protocol (TCP), which provides a reliable end-to-end data transfer service.
   3. Process/application layer:
      1. File transfer protocol (FTP), which is a simple application for transfer of ASCII, EBCDIC and binary files.
      2. Simple mail transfer protocol (SMTP), which is simple electronic mail facility.
      3. Telnet protocol (TELNET): which provides a simple asynchronous terminal capability?

  Discuss about the operation of TCP/IP protocols with suitable diagram.

  

TCP and IP protocol are configured for communications. The total communications facility may consists of multiple networks; the constituent networks are usually referred to as subnetworks. Some sort of network access protocol is used to connect a computer to a subnetwork. This protocol enables the host to send data across the subnetwork to another host or, in the case of a host on another subnetwork, to a router. IP is implemented in all of the end systems and routers. It acts as a relay to move a block of data from one host, through one or a more routers, to another host. TCP is implemented only in the end systems; it keeps track of the blocks of data and assures that all are delivered reliably to the appropriate application.

For successful communication, every entity in the overall system must have a unique address. Actually, two levels of addressing are needed. Each host on a subnetwork has a unique global internet address; this allows the data to be delivered to the proper host. Each process with a host must have an address that is unique within the host; this allows the host-to-host protocol (TCP) to deliver data to the proper process. These latter addresses are known as ports.

Suppose that a process, associated with port 1 at host A, wishes to send a message to another process, associated with port 2 at host B. The process at hands the message down to TCP with instructions to send it to host B, port 2. TCP hands the message down to IP with instruction to send it to host B. Next, IP hands the message down to the network access layer with instructions to send it to router X

To control this operation , control information as well user data must be transmitted, as in figure(below). The sending process generates a block into smaller pieces to make it more manageable. To each of these pieces, TCP appends control information known as the TCP header, forming a TCP segment. The control information is to be used by the peer TCP protocol entity at host B. Examples of items that are included in this header are Destination port, Sequence number and checksum.

Next, TCP hands each segment over to IP, with instruction to transmit it to B. These segments must be transmitted across one or more subnetworks and relayed through one or more intermediate routers. This operation requires the use of control information. Thus IP appends a header of control information to each segment to form an IP datagram. An example of an item stored in the IP header is the destination host address.

Each IP datagram is presented to the network access layer for transmission across the first subnetwork in its journey to the destination. The network access layer appends its own header, creating a packet, or frame. The packet is transmitted across the subnetwork to router X. The pocket header contains the information that the subnetwork needs to transfer the data across the subnetwork. Examples of items that may be contained in this header include Destination subnetwork address and Facilities requested.

At router X, the packet header is stripped off and the PP header examined. On the basis of the destination address information in the IP header, the router directs the datagram out across subnetwork 2 to B. To do this, the datagram is again augmented with a network access header.

When the data are received at B, the reverse process occurs. At each layer, the corresponding header is removed, and the remainder is passed on to the next higher layer until the original passed on to the next higher layer until the original user data are delivered to the destination process.