Just wanna take a moment to briefly explain the communication modes you will find in networking.
We have Four (4) communication modes:
1. Unicast: This is referred to as one-to-one communication.
In a scenario where one device sends data to ONLY one device at a time, that is an example of a unicast message.
2. Multicast: This is referred to as one-to-many communcation
In a multicast mode of communication, messages are sent from one source to multiple destinations at the same time.
A good example of a multicast message can be where you have a classroom full of people, and you walk in with a wish to speak to only those with brown hair. That way, you (the source) sends the message to only those group of people (one-to-many), out of the total number of people available.
3. Broadcast: This is referred to as one-to-all communication.
Broadcast messages are sent from one source to every destination connected to the source.
A good example of a broadcast is a radio. Everyone tuned in to that radio station will get the messages being transmitted, whether it is intended for them or not.
Having broadcasts on a network can significantly slow down activities, as the whole network could be flooded with messages not meant for everyone being broadcasted to everyone connected.
4. Anycast: This is referred to as one-to-nearest communication.
This communication mode is being utilized by IP version 6 (IPv6) and allows a form of communcation where a device communicates with the nearest of multiple destinations that can respond to its request.
This means that if there are say, two destinations that can receive and respond to the request initiated by a device, using anycast communication mode, only the "nearest" destination would respond.
IP version 4 (IPv4) makes use of Unicast, Multicast and Broadcast modes of communication, while IP version 6 (IPv6) makes use of Unicast, Multicast and Anycast modes of communication.
Wednesday 29 July 2015
Network Devices
Okay, so I was talking to a few friends today about networking, and I decided to introduce them to it.
After explaining the general concept behind computer networking, I felt there was a need to show them a few devices and explain what those devices do.
Well, networking is made possible by connecting devices together, and these devices are simply called network devices.
Examples of network devices are: Hubs, Switches, Routers, Access Points, Firewalls, etc.
Let me briefly talk about each of the above mentioned devices.
Hubs: Think of a hub like a cable with ports on it. Hubs really don't do anything apart from broadcasting whatever they receive to everyone connected to it. A hub is NOT intelligent, since it can not make decisions on whether or not to forward the data it receives; it just sends it to everyone.
Switches: A switch can sometimes be called an intelligent hub. This device is still one of the most widely used network devices today. A switch has three main functions:
1. Address Learning - This is usually the first thing a switch does before it can perform its other functions. Switches learn addresses called MAC (Media Access Control) Addresses, which is really a unique address for every network capable device. Once a switch has learnt addresses connected to it through its ports, then it is easy to forward data to only the intended recipient, as opposed to forwarding data to everyone (like a hub does)
2. Forward & filter frames - A switch can filter frames, as well as forward it if no filtering is required. Meanwhile, a frame is what data is called at the point where it encounters a device such as a switch. More details about that later.
3. Loop avoidance - A switch has a way of making sure that there are no loops in data transfer. This characteristic makes it a much more preferable device than a hub, since certain things (which will be talked about later) can be done to determine what is sent, and where it should be sent to.
Routers: A router is a device that connects various networks together. It has 4 main functions:
1. Packet Switching - A router can easily switch a packet from one point to another.
2. Packet Filtering - A router can filter packets, and decide whether or not to forward them.
3. Path selection - A router can weigh various options, and determine the best path through which a packet should be sent in order to get to its destination safely.
*Meanwhile, a packet is what data is called at the point where it encounters a device such as a router*
4. Internetwork communication - Once a router is connected to more than one network, it can allow users on different networks to communicate and share resources.
Access Points: An access point, widely known as Wireless Access Point, is a device that allows users to connect to a network wirelessly. This means that users do not need to connect through network cables in order to access the resources that are being shared on a network.
Firewalls: A firewall is a security device that either permits or denies data traffic to a network. A firewall can be configured to accept/deny traffic based on different criteria; and this is usually dependent on the security policy of the organization involved.
So, you can see how interesting it is just knowing about some of these devices. After talking about these to my friends, I could see smiles on their faces, and I'm sure you've gained enough to put one on your face too.
Feel free to ask questions and make contributions.
After explaining the general concept behind computer networking, I felt there was a need to show them a few devices and explain what those devices do.
Well, networking is made possible by connecting devices together, and these devices are simply called network devices.
Examples of network devices are: Hubs, Switches, Routers, Access Points, Firewalls, etc.
Let me briefly talk about each of the above mentioned devices.
Hubs: Think of a hub like a cable with ports on it. Hubs really don't do anything apart from broadcasting whatever they receive to everyone connected to it. A hub is NOT intelligent, since it can not make decisions on whether or not to forward the data it receives; it just sends it to everyone.
Switches: A switch can sometimes be called an intelligent hub. This device is still one of the most widely used network devices today. A switch has three main functions:
1. Address Learning - This is usually the first thing a switch does before it can perform its other functions. Switches learn addresses called MAC (Media Access Control) Addresses, which is really a unique address for every network capable device. Once a switch has learnt addresses connected to it through its ports, then it is easy to forward data to only the intended recipient, as opposed to forwarding data to everyone (like a hub does)
2. Forward & filter frames - A switch can filter frames, as well as forward it if no filtering is required. Meanwhile, a frame is what data is called at the point where it encounters a device such as a switch. More details about that later.
3. Loop avoidance - A switch has a way of making sure that there are no loops in data transfer. This characteristic makes it a much more preferable device than a hub, since certain things (which will be talked about later) can be done to determine what is sent, and where it should be sent to.
Routers: A router is a device that connects various networks together. It has 4 main functions:
1. Packet Switching - A router can easily switch a packet from one point to another.
2. Packet Filtering - A router can filter packets, and decide whether or not to forward them.
3. Path selection - A router can weigh various options, and determine the best path through which a packet should be sent in order to get to its destination safely.
*Meanwhile, a packet is what data is called at the point where it encounters a device such as a router*
4. Internetwork communication - Once a router is connected to more than one network, it can allow users on different networks to communicate and share resources.
Access Points: An access point, widely known as Wireless Access Point, is a device that allows users to connect to a network wirelessly. This means that users do not need to connect through network cables in order to access the resources that are being shared on a network.
Firewalls: A firewall is a security device that either permits or denies data traffic to a network. A firewall can be configured to accept/deny traffic based on different criteria; and this is usually dependent on the security policy of the organization involved.
So, you can see how interesting it is just knowing about some of these devices. After talking about these to my friends, I could see smiles on their faces, and I'm sure you've gained enough to put one on your face too.
Feel free to ask questions and make contributions.
Tuesday 28 July 2015
Computer Networks and Classifications
A computer network is a collection of computers for the purpose of information exchange. This exchange of information is made possible through network media such as cables. Networks can be either wired or wireless.
Computer networks differ in size, as well as the kind of data that is shared across the network.
Networks are classified into 3 main categories, namely:
Local Area Network (LAN): This kind of network is usually set up in a small geographic area; usually covering a small room or up to a single building. A good example of a Local Area Network is a home network set up to provide basic file sharing between users, as well as basic internet connectivity.
Metropolitan Area Network (MAN): This kind of network covers a much larger geographic area than a LAN. Such networks are usually city or nation wide, and connects multiple network devices in different locations. A good example of a Metropolitan Area Network is a network that services say, a bank with branch offices across various states of a country.
Wide Area Network (WAN): This is the largest of the three classifications of computer networks. There is virtually no limit to how large a WAN can be, as it connects networks across countries and contents. The internet is the largest Wide Area Network in existence.
Your knowledge of what a computer network is, as well as its classifications, will help you to better understand other concepts that will be touched in subsequent posts.
Welcome on board.
Computer networks differ in size, as well as the kind of data that is shared across the network.
Networks are classified into 3 main categories, namely:
Local Area Network (LAN): This kind of network is usually set up in a small geographic area; usually covering a small room or up to a single building. A good example of a Local Area Network is a home network set up to provide basic file sharing between users, as well as basic internet connectivity.
Metropolitan Area Network (MAN): This kind of network covers a much larger geographic area than a LAN. Such networks are usually city or nation wide, and connects multiple network devices in different locations. A good example of a Metropolitan Area Network is a network that services say, a bank with branch offices across various states of a country.
Wide Area Network (WAN): This is the largest of the three classifications of computer networks. There is virtually no limit to how large a WAN can be, as it connects networks across countries and contents. The internet is the largest Wide Area Network in existence.
Your knowledge of what a computer network is, as well as its classifications, will help you to better understand other concepts that will be touched in subsequent posts.
Welcome on board.
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