How do protocols work

Network protocols are the reason you can easily communicate with people all over the world, and thus play a critical role in modern digital communications. Neither local area networks LAN nor wide area networks WAN could function the way they do today without the use of network protocols. Network protocols take large-scale processes and break them down into small, specific tasks or functions.

This occurs at every level of the network, and each function must cooperate at each level to complete the larger task at hand. The term protocol suite refers to a set of smaller network protocols working in conjunction with each other. Network protocols are typically created according to industry standard by various networking or information technology organizations. While network protocol models generally work in similar ways, each protocol is unique and operates in the specific way detailed by the organization that created it.

Billions of people use network protocols daily, whether they know it or not. Every time you use the internet, you leverage network protocols. Though you may not know how network protocols work or how frequently you encounter them, they are necessary for using the internet or digital communications in any capacity.

How does it 'talk' to other computers connected to the Internet? An example should serve here: Let's say your IP address is 1. The message you want to send is "Hello computer 5. Obviously, the message must be transmitted over whatever kind of wire connects your computer to the Internet. Let's say you've dialed into your ISP from home and the message must be transmitted over the phone line. Therefore the message must be translated from alphabetic text into electronic signals, transmitted over the Internet, then translated back into alphabetic text.

How is this accomplished? Through the use of a protocol stack. Every computer needs one to communicate on the Internet and it is usually built into the computer's operating system i.

Windows, Unix, etc. Hardware Layer Converts binary packet data to network signals and back. If we were to follow the path that the message "Hello computer 5. If the message to be sent is long, each stack layer that the message passes through may break the message up into smaller chunks of data.

This is because data sent over the Internet and most computer networks are sent in manageable chunks. On the Internet, these chunks of data are known as packets. Each packet is assigned a port number. We need to know which program on the destination computer needs to receive the message because it will be listening on a specific port. This is where each packet receives it's destination address, 5. Now that our message packets have a port number and an IP address, they are ready to be sent over the Internet.

The hardware layer takes care of turning our packets containing the alphabetic text of our message into electronic signals and transmitting them over the phone line. On the other end of the phone line your ISP has a direct connection to the Internet. The ISPs router examines the destination address in each packet and determines where to send it.

Often, the packet's next stop is another router. More on routers and Internet infrastructure later. Eventually, the packets reach computer 5. As the packets go upwards through the stack, all routing data that the sending computer's stack added such as IP address and port number is stripped from the packets.

When the data reaches the top of the stack, the packets have been re-assembled into their original form, "Hello computer 5. But what's in-between? What actually makes up the Internet? Let's look at another diagram: Diagram 3 Here we see Diagram 1 redrawn with more detail. The physical connection through the phone network to the Internet Service Provider might have been easy to guess, but beyond that might bear some explanation.

The ISP maintains a pool of modems for their dial-in customers. This is managed by some form of computer usually a dedicated one which controls data flow from the modem pool to a backbone or dedicated line router.

This setup may be refered to as a port server, as it 'serves' access to the network. Billing and usage information is usually collected here as well. From here the packets will usually journey through several routers and over several backbones, dedicated lines, and other networks until they find their destination, the computer with address 5. But wouldn't it would be nice if we knew the exact route our packets were taking over the Internet? As it turns out, there is a way This one is called traceroute and it shows the path your packets are taking to a given Internet destination.

Like ping, you must use traceroute from a command prompt. In Windows, use tracert www. From a Unix prompt, type traceroute www. Like ping, you may also enter IP addresses instead of domain names. Traceroute will print out a list of all the routers, computers, and any other Internet entities that your packets must travel through to get to their destination. If you use traceroute, you'll notice that your packets must travel through many things to get to their destination. Most have long names such as sjc2-core1-h These are Internet routers that decide where to send your packets.

Several routers are shown in Diagram 3, but only a few. Diagram 3 is meant to show a simple network structure. The Internet is much more complex. Internet Infrastructure The Internet backbone is made up of many large networks which interconnect with each other.

These networks peer with each other to exchange packet traffic. NAPs were the original Internet interconnect points. Below is a picture showing this hierarchical infrastructure. Hence, protocols provide a common language for network devices participating in data communication. Protocols are developed by industry-wide organizations. Support for network protocols can be built into the software, hardware, or both. All network end-users rely on network protocols for connectivity.

There are different layers for instance, data, network, transport, and application layer, etc. It is the communication between entities in different systems, where entities can be a user application program, file transfer package, DBMS, etc. Hence protocols can be implemented at the hardware, software, and application levels. A standard protocol is a mandated protocol for all devices. It supports multiple devices and acts as a standard.

Standard protocols are not vendor-specific i. Proprietary protocols are developed by an individual organization for their specific devices. We have to take permission from the organization if we want to use their protocols. It is not a standard protocol and it supports only specific devices. We may have to pay for these protocols.

The key elements of the protocol determine what to be communicated, how it is communicated, and when it is communicated. Syntax refers to the structure or format of data and signal levels. It indicates how to read the data in the form of bits or fields. It also decides the order in which the data is presented to the receiver. Example: A protocol might expect that the size of a data packet will be 16 bits.