Network Protocols For computer Networking

Network Protocols:

Protocols are the agreed upon ways in which computers exchange information.

Protocols that work together to provide a layer or layers of the Open System Interconnection model are known as protocol stack or suite.

Standard protocol stacks:

•  The ISO/OSI protocol suite
•  IBM System Network Architecture (SNA)
•  Digital DECnet                    ,  AppleTalk
•  Novell NetWare       , TCP/IP

A protocol is a set of basic steps that both parties must perform in the right way.

 For one computer to send a message to another computer, first computer must perform the following steps:

1. Break the data into small section called packets
2. Add addressing information to the packets identifying the destination computer
3. Deliver the data to the network card for transmission over the network

The receiving computer must perform the same steps but in opposite order:

1. Accept the data from the network adapter card.
2. Remove the transmitting information that was added by the transmitting computer.
3. Reassemble the packets of data into the original message.

 Networks primarily send and receive the small chunks of data called packets.

Packet structure: Packets have the following components:

1. A source address specifying the sending computer.
2. A destination address.
3. Instructions that tell the computer how to pass the data along.
4. Reassembly information for when the packet is part of a longer message.
5. The data to be transmitted to the remote computer.
6. Error-checking information to ensure that the data arrives intact.

 The components are combined into three sections:

•  Header: Includes alert signal to indicate that the data is being transmitted, source and destination addresses and clock information to synchronize the transmission.
•  Data: The actual data being sent. This can vary from 48 bytes to 4K.
• Trailer: The contents of the trailer varies among network types, but it typically includes a CRC. CRC helps the network determine whether a packet has been damaged in transmission

Microsoft-Supplied Network Protocol:

• NetBEUI
• NWLink
• TCP/IP
• NetBEUI

NetBEUI: It stands for NetBIOS Extended User Interface. Microsoft included NetBEUI 3.0 with Windows NT. (Originally it is developed by IBM)

Advantages of NetBEUI:

• High speed on small network
• Ability to handle more than 254 sessions
• Better performance over slow serial links than previous versions
• Ease of implementation
• Self-tuning features
• Good error protection
• Small memory overhead

Disadvantages of NetBEUI:

• It cannot be routed between networks
• Few tools for NetBEUI such as protocol analyzer
• It offers very little cross-platform support

NWLink:

NWLink is Microsoft’s implementation of Novell’s IPX/SPX protocol stack, used in Novell NetWare.