Week 4: Day 012 - Cabling/Topology #3

Today, I will finish off the section on Cabling/Topology! So last week I left off on Twisted Pairs, CAT ratings and MHz (Megahertz) after thoroughly going through coaxial cables. Now, let's take a look at the other cables.

So next up is the Fiber-Optic cable (spelled Fibre-Optic in other English speaking countries) which is different from the cables before. This cable astounds me as it transmits LIGHT, rather than electricity! Crazy isn't it?! The problem here, is as usual, the amount of attractions for EMI. However, if you thought the astonishment would end there, you're wrong. This, unlike copper cables, can travel to distances up to 10 KILOMETERS! Again, that's pretty crazy. But how is this done? The make up of a fiber-optic cable according to my textbook is the "glass fiber"(the core), the "cladding" (this makes the light reflect down the fiber), the buffer (gives material strength), and the "insulating jacket". These cables are made with much variety in the core and cladding. Cable manufacturers use two-number designators to define those two elements of the cable. The most common size of the fiber-optic cables is 62.5/125 um (can't really do the symbol haha.) Most fiber-optic cables use pairs of fibers, one for sending the other for receiving. This is called "duplex fiber-optic cabling". This type of cabling is tiny, and there are two types that accept two different types of lighting. In my case, if I required a fiber-optic cable for networking (probably not) then I would use fiber optics that use LEDs (Light Emitting Diodes) to get the light signals across. Those types of cables are known as MMF (multimode fiber.) The other type is an SMF (Single-mode fiber) which uses lasers (cool!) and this type prevents a common issue with MMF's and that's "modal distortion", when signals sent at the same time don't arrive at the same time, because of differing cable lengths. The way these cables interpret the wavelengths of light is in nanometers (nm). MMF's transmit 950-nm wavelengths while the SMF transmits 1310 or 1550 nm, depending on which laser. Fiber-optic cables come in a variety of connector types. What is important to know for the Network+ exam is ST, SC, and LC (LC especially because of it's duplex connector which accepts two fiber cables.)

Wow, that was long! Don't worry the rest of the chapter may be a variety of cables, but not too much info. So first off is the "Classic Serial"  cabling, which is super ancient lol and it predates networking and PC's! RS-232 is the "recommended standard" in which serial communication took place on a PC. It hasn't changed much obviously, and when the PC came out they were the only standard. Because of these, companies like IBM put two ports for serial networking on every PC. You still find them on there to this day! The most common type is a "male" DB-9 which is a 9-pin serial port. Not surprisingly, nowadays serial networking is sucky and terrible. It has slow data rates of 56,000 bps (that's right BYTES per second) and only do point-to-point connections. Continuing, let's stay in the past. Now we have "Parallel" connections. The textbook literally characterizes this and serial networking as ancient haha (do you even remember this back in the day Mr. Elkner???). Anyways, this is also a limited point-to-point topology and uses a 25-pin "female" instead of a male DB connector. That's literally all to say for both serial and parallel. Now there's FireWire. This is the only good alternative cabling option to UTP or fiber-optic cables. It's again, restricted to point-to-point connections, but is actually very fast! It has its own connector as you could imagine. Going towards the end of my blog entry, let's start talking about standards. In terms of FireWire, the NEC (National Electrical Code) and the Underwriters Laboratories work together in making "fire ratings". The two common ones are PVC (polyvinyl chloride) and plenum. Cable with PVC has virtually no protection from fire. Even worse it creates toxic fumes! Plenum however is much safer, but more expensive at that. Most cities require the network installations of ONLY those types of cables. The reason that it's called "plenum" is that the space between the ceiling of a hypothetical office, and it's legitimate concrete ceiling is called the "plenum". A third rating, which isn't very notable sense it isn't standard or as safe as plenum, is the "riser" rating. I just thought that was worth noting.

Finally, let's talk about some big standards. The "Network Industry Standards" created by the IEEE (Institute of Electrical and Electronics Engineers) defines the standards in the implementation of technology. Some history, in February of 1980 it was taken over by the 802 Working Group, which was a company given the job of developing standards. So the IEEE 802 created many cabling standards. However, there are many IEEE committees which create standards for many electronic devices such as printers or even FireWire. Anyways, even more bureaucracy and fragmentation occurred when subcommittees were also created (ex: IEEE 802.3, or 802.5). Of course as you can imagine, many of these committees and subcommittees have been disbanded. To finish, it should be noted that for the Network+ exam, you should definitely know the IEEE 802.3 and 802.11 standards. Thanks for reading, and tschuss!

Week 4: Day 011 - Cabling/Topology #2

Last class, I spent all class-time installing Linux into all the computers in the lab. Fortunately my peer and I were able to install it on all of them in time. Today, I will continue with the Cabling/Topology, but the rest of the chapter is really just about Cabling, as a note.

So let's start with talking about the coaxial cable. This cable is a "central conductor wire" as characterized in the textbook. The cable is literally just a bunch of shielding (metal shields) so data can travel safely without being interrupted by EMI (Electromagnetic Interference.) To be honest, anything that runs on electricity can interrupt the data transfer (ex: printers, fans, fridges.) Unfortunately, the NIC's would misinterpret the signals, which ends up shutting down the network. Referring back to the topologies, the Early-Bus topology networks would often use coax cables. However, nowadays it's simply used for cable modems in connecting to its ISP (Internet Service Provider) and connecting TV's and to Satellite Receivers or Cable Boxes. The head of the cable has an "F-Connector" used for screwing on to keep a secure connection. The more dominantly used cable, today, is the RG-6 (and almost never the RG-59.) These cables each have an RG (Radio Grade rating) which are developed by the United States military. But the most important number to look at on the cable is the "Ohm rating" which measures the amount of resistance put on the cable. The ratings are seen on the cables, and RG-6 and RG-59 both have 75 Ohms. Sometimes, you'll need to split a coax cable, and luckily there are coaxial splitters thanks to its popularity in today's world.

Next up, we have the Twisted Pair cables which are usually Shielded or not. These cables are the most common types used in networks. The cabling is made up of several wires which are twisted around each other. The STP (Shielded Twisted Pair) is exactly what is said in the name. It's a twisted pair surrounded by shielding, once again protecting it from EMI. These cables are surprisingly rare as there isn't a lot of need for shielding. A situation in which it is needed, is obviously when there is a lot of electronic disruptions and signals being thrown around the room. Now the UTP (Unshielded Twisted Pair) is the most common type of network cabling used. This cable is much cheaper than than the STP, but you must be careful for interference when installing the cable. Thankfully, the UTP cable provides a cheap and efficient way to run cable networks, but it's not exclusive to just cable networks. Other tech such as telephones use the same type of cabling. Sometimes this can confuse, because you may find the same set of cables, for those two different uses. However, to differentiate both, UTP cables have variations. These variations are known as CAT (Category ratings.) They are categorized in MHz (Megahertz) which tells you what the highest frequency is for each cable. What a megahertz is in a nutshell, is the cycles per second in a cable. An example in the textbook was that a 10 MHz cable could handle 10 million bits (10 Mbps) and the maximum amounts of data that can go through the cable per second is known as "bandwidth". Current networks have "bandwidth-efficient encoding schemes" which basically means, they cram as many bits as they can into the same signal, if the cable can handle it. Most networks run at 1000 MHz, and the common cabling used is CAT 5e, which is cheaper than CAT 6. In the future, CAT 6 will probably be used commonly. It's a great idea to be able to look at UTP and being able to figure out its CAT rating. The two places to look is in the box it came in, or on the cable itself. People who have set up telephones in the past, have probably seen RJ (registered jack) connectors used in UTP cables. As a quick note, telephones use RJ-11 connectors while networks use four-pair RJ-45 connectors. This concludes my blog entry, next time I will probably finish off this chapter. Thanks for reading, and tschuss! 

Week 3: Day 010 - Cabling/Topology #1

Hello everyone, today is the start of my third week working towards the Network+ Certification. Now I've moved on to the next part of my textbook which focuses on Cabling (not to be confused with the sections on Ethernet cabling.) This bit is not one that is too important according to my teacher, but I will still cover it.

To begin, cabling is sometimes essential in a network, since information must be transferred from system to system. However, this does not matter sometimes if the network sends information wirelessly. Now let us start with a focus on what Topology is. Networks use many topologies to connect computers together. These types are the old ones "bus, ring, and star" and the modern ones "hybrid, mesh, point-to-multipoint, and point-to-point".

Let's talk about "Bus and Ring". The first networks used only one of the two topologies. A bus topology uses one cable that connects all computers in a line, while a ring topology does it in a ring. Data flows differently between bus and ring networks. In bus, the data from the computers go out on a bus, really. It's in the name. A network then has terminators on either end to stop signals from reflecting on the end of each of the end cables. However, in a ring topology, the data moves in a circle (like a ring) from one computer to the next one in the same direction, without end (termination cables.) Although these networks reliably work, the problem is that if just one of the cables breaks, then so does the network.

The next topologies I will talk about are Stars and Hybrids. The star topology has a central connection box, and all the computers connect straight to it. Now the good thing about this, is if one cable fails then there is room for error, as the network is not effected. The Hybrid topology is basically an easier topology to use, as smart network engineers found a way to taking the ring topology (and bus topology) and direct it into a tiny box. Now, people may say that it looks like the star topology, well yes it does, but the signals were actually more similar to the bus and ring topologies. Nowadays topologies are split into two types "logical and physical" one relates to what the setup looks like, and the other to how the signals are actually transmitted. Now this, in reality, is what the hybrid topology really is, just a hybrid. By this I mean that a physical topology from one topology is combined with the logical one of another. Make sense?

Now it's on to the Mesh and Point-to-Multipoint topologies. The mesh topology is when every computer on the network is physically connected. That's crazy and too tedious in my opinion! In a partially-meshed one there are at least two devices connected, while in the fully-meshed one every single computer is connected to each other! However, this network is the most reliable of all, but realistically speaking, it's also the most expensive haha. Then there's the the point-to-multipoint topology. This is literally just like the star topology except with an intelligent device in the middle (usually a computer) rather than a box. Finally I will speak about the point-to-point topology. This one is literally just two computers connected to each other. That's all.

To conclude this entry, I have to just say, that even though a topology shows how systems in a network should connect physically, it is not specific or not. Where's the part showing you what type of cable you need? or what length? Well the topology isn't supposed to tell you this stuff, instead there are manufacturers and standards that have been set over the years, and in simple terms this is called "network technology" and it shows you how to apply these topologies. We'll talk about that later, but for now, thanks for reading, and tschuss!

Week 3: Day 009 - Ethernet Basics #1

Hello everyone, today I'm taking a detour in the Network+ course, and will be skipping to the Ethernet cables section, as tomorrow I have a decorated cable maker showing me exactly how to make a cable functional. For this very reason, I will skip over the Cable and Topology section to learn about Ethernet cables.

To start off, let's learn a brief history of the Ethernet. In 1973 Xerox created the Ethernet cable to transport data without having to move data through data disks. The rate was a (now) measly 3 mbps. Later in 1979 they looked to promote Ethernet, and found partners such as Intel to sponsor it. By then they had improved it so it had a transfer rate of 10 mbps. The Ethernet standard was controlled by the IEEE which created a committee just for the cable called 802.3 Committee.

Now let's look at the Topology of it. Since the 90s all Ethernet cables have used what is known as a "hybrid star-bus topology". Instead of switches, people used hubs which was just a repeater and interpreter of the binary codes coming in from one port and sending a signal to other ports. But how does it interpret the data that is going in and out?

Well, each Ethernet frame is organised into seven pieces of information. As stated before, the sending computer will make it so other computers are not allowed to use the cable until it is done transferring the data. When a data frame is corrupted, the sending computer will retransmit it until the data makes it to its destination. Now let's look at the seven pieces of a frame: The Preamble, the MAC Addresses of the sending systems, as well as the receiving system, there's also the type of data, a pad, the data, and a CRC (Cyclic Redundancy Check.)

All the preamble is, is a set of 64-bit binary code which all end in 11. It is meant to give time for the receiving NIC to expect a data frame. That's all with that, now the MAC Addresses. So as we know the MAC Address is generally used as an identifier for an NIC, and it still is in this case. The Ethernet is meant to identify the MAC Address. So when the data frame arrives at the hub, the hub is able to create a copy of the frame for every port. With that said, there is also a security vulnerability that comes with this process. Network diagnostics programs or "sniffers" have the ability of making your NIC run in "promiscuous mode" which makes the NIC read all data, regardless of its recipients' MAC Address. Although it's a good tool for troubleshooting, it does not discriminate against people with malicious intent.

Continuing, I will talk more about the "Type, Data, Pad, and FCS (Frame Check Sequence)". The type of Ethernet frames vary on the data it's sending. This helps differentiate the data, like if it were carrying IPv4 or IPv6 data. However this field does not specify the level of data it's carrying (like if it were an e-mail or webpage.) Now the data is the cargo of the frame. If it's an IP packet it carries information about the recipient and sender IP. Now, since the minimum Ethernet frame is 64-bytes when a frame is smaller than that a pad is used. The pad is basically a way of compensating by adding more data to the frame so it fits the minimum requirement. Finally, there is the Frame Check Sequence which is a CRC (Cyclic Redundancy Check) that enables Ethernet to detect any bad corruption within data. For detecting errors, the computers add codes to each frame. The sending device adds a calculation formula so the receiving computer can determine whether the frame is good. If it's not, then the receiving computer asks for a re-transmission. That's where this entry ends. Yes, it was pretty long. But be expecting a short entry on how to make the most popular types of Ethernet cables. Thanks for reading, and tschuss!                      

Week 3: Day 008 - Linux and Lubuntu

So, today I've been given a PC in the room exclusive for the use of Linux. This system is equipped with the most lightweight version of Linux (and Ubuntu) out there, known as Lubuntu. For those of you who want more Network+ posts, there will be one tomorrow, but for now I will post my plans for this blog in terms of what I will post in the future regarding Networking and Linux.

Firstly, I will be making some posts regarding real life activities I do regarding the creation of a network. Chances are I will be using IPCop and trying to create a network in the classroom for my peers to test out. This would be a great experience and I would feel much satisfaction from their use. My teacher suggests that I do not transmit the SSID so people going about with laptops don't get in on our network. Additionally, there is a Cisco lab available for me to use, and that's great! I will be using that for sure.

Secondly,  I will start messing around with cables, maybe when I start my sections for ethernet then it will be a good idea to do it. When I get to that point my teacher would like me to test some of the cables or perhaps make some of them usable, which is great information to know for a tech.

Finally, you should anticipate me uploading photos of me doing this stuff with explanations as to what I'm doing. However, this might take a bit longer so maybe I will do posts every other day by that point (hopefully it doesn't come to that.) So I have a good plan as to what I will be doing in the near future.

In conclusion, this is meant to let you know what I will do the rest of the year, give you a general idea what will happen and what my set-up is. Stay tuned folks, there is a lot to come!

Week 2: Day 007 - TCP/IP (Continued)

Hello again! I'm back with some more informational posts to prepare for my Network+ certification. I will continue where I left off (which is at TCP/IP's transport layer.)

Let's start then; so last time I said that the Transport layer is responsible for managing important tasks such as VoIP's (Voice-Over IP) and I identified the differences between TCP and UDP. Now let's talk about TCP segments. When a packet has its IP removed, there is a container known as a "TCP segment" which checks whether the data is going to the right destination. Parts of these segments are known as "Cheksums" and "Flags" (maybe I will delve into what those are later.) The TCP and UDP protocols are then responsible for breaking down data and adding ports to data coming in from the Application layer, and that is the next layer.

So, the next layer, and last layer is known as the "Application Layer" and in comparison to the OSI model it includes the last three layers, the Session, Presentation, and Application layers. Every application must know how to control remote systems (in particular the connection based apps.) TCP/IP applications are each given a unique port number. Some of them are extremely popular for different reasons. For example, some ports are used for gaming servers which makes them popular among gaming server hosts and gamers in general. In the TCP/IP model the API (Application Program Interface) is a part of the Application layer (like the OSI model); However, by definition all applications are aware of their networks. Every TCP/IP application needs to talk to the network to function properly. This is essential for using internet browsers and playing multiplayer video games.

Finally, to summarize, the Application Layer programs generate data, the Transport Layer break the data into chunks and assign them to either the TCP or UDP protocol. The Internet Layer hands out IPs and creates IP packets. Then the Link Layer puts the IP packet into frames using MAC addresses and FCS (Frame Check Sequence). At this point the data is ready to go through ethernet or wireless.

In conclusion, the OSI Seven-Layer Model and the TCP/IP model provide great models which make it easier for people to diagnose issues. This can be used in cases such as a device that is not working properly over the network. By "easier to diagnose" I'm essentially saying troubleshooting is not difficult as it comes down to process of elimination. You look for activity on each layer, whether it's working properly or not is where you will find the base of the problem. Now I will leave you with this thought, learning these models are essential to know as it will be a tool for troubleshooting. On that bombshell, goodbye!

Week 2: Day 006 - Bypassing APS Configuration

So, today I have no Network+ blog entries for you. However, I will tell you about what I have been doing today, cause I haven't been doing nothing haha. Basically, the APS (Arlington Public Schools) configuration systems that they have on each computer is a bit illogical.

To start, they have a password for their student profiles on Windows 7, and won't give it to any of the teachers or staff! I mean, if you want to lower the amount of tickets being submitted, then don't bloody do that! So to end this nonsense we decided to REMOVE the password, using an admin account. This was successful, up until the point where they were being denied login entry into the student account. This was a problem for the last couple of days.

Turns out that the problem was one that I logically solved for them, by deciding to go straight into the "APS Student" login screen and typing nothing and clicking enter. It got me in, and that ended that problem.

So from there, he wanted me and one of my peers to go around the room and install Notepad++ and update Java on all the computers in the room. That took a while with all the restarting we did. In the end, we pretty much did it to all the computers we could, given the fact that testing was being performed in the room.

To conclude, I am thrilled that we were able to fix the issue. In the coming days I will probably do some hands on things, and probably take some screenshots to help. Finally, I will be doing my regular Network+ blog posts probably next time. Until then, Auf Wiedersehn!

Week 2: Day 005 - TCP/IP

Finally, the time has come for me to learn the most important network model on Earth! This is known as the TCP/IP model and it's essential for a tech to know. (Once again) Today, I will summarize my lessons on this blog. Also it's important to remember that a lot of basic info was already covered in the previous blogs on the OSI Seven Layer Model, since the TCP/IP model is not very different, just way more efficient.

Let's begin by giving some background info and stating the layers of TCP/IP. So, back in the day the OSI Model was made to universally connect the different protocols from different manufacturers. In today's world the OSI Seven Layer model is not important but it is something that many techs know to understand the basics of networks. The most important network model is TCP/IP for sure! To have that old system in a world of single protocol suites is illogical, so that's why the TCP/IP system is so essential in our world and why we must know it. Now, the layers are as follows: Link/Network Interface, Internet, Transport, and Application. There is not much standardization in the system, which makes it great for varietal purposes. To give a good example the Link Layer is also widely known as the Network Interface Layer. This brings me to the first layer.

The first layer is known as the "Link Layer" and the "Network Interface". What this layer essentially does is combine Layer 1 & 2 of the OSI model into one layer. There's not much to say for this layer, or some of the others (especially according to my textbook) but I will try to explain good ways of distinguishing the different layers. To seperate some layers think of the packets and frames. The part of the network that deals with frames is the Link Layer. When the IP packet is opened then you move on to the Internet Layer.

The second layer is the "Internet Layer". To really summarize this, the Internet layer focuses mainly on IP packets. Anything that deals with IP packets is a part of the Internet layer. IP addressing and the delivering of the packets are all in itself also a part of the Internet Layer. That's all there is to say really (if you want more in-depth information of some layers, I cite the earlier posts in my blog.)

The third layer is the "Transport Layer" which combines some parts of the OSI Transport Layer, the OSI Session Layer, and even the Application layer (on the OSI model)! The TCP/IP model is very busy working with assembling and disassembling data, but it defines other functions that may be connection or connection-less communications. The POP (Post Office Protocol) is used for sending and verifying e-mails and messaging. It's great because it makes sure that the message is not corrupt! In addition there are other TCP/IP protocols used for VoIP (Voice-Over IP). This brings me to a very important aspect of this layer, TCP and UDP. The TCP (Transmission Control Protocol) is connection-oriented, while UDP (User Datagram Protocol) is not. And that's where I will end it for now! Keep checking the blog, new entries daily. Bis bald.

Week 2: Day 004 - OSI Layers 4-7

Hello again! So I was not able to post yesterday since I was taking my English entry test for NOVA, but now I'm back, and I will finish off my independent lesson on the OSI Layers. I will also likely make another post to make up for yesterday, so be alert for two consecutive posts!

So, let's start out with Layer 4, (since last time I went through up to the Network layer) this is known as the "Transport" layer. This layer has the responsibility of chopping up, organizing, and sending data. Usually the amount of data is too large for a single frame, so the data must be broken and put into several frames for sending. Once this process is complete the sending computer will give the data to the NIC. When the receiving computer gets the data it will recognize this packets are being sent to it, and will verify that the data is not corrupted. This entire process is directed by the "transport protocol", the protocol is set to give each packet a sequence number. The process proves to be one of the most important as it is responsible for the assembling and disassembling of data.

Next, there is Layer 5 which is known as the "Session" layer. A network has many systems, and usually they are talking to each other very often. For example, say there was a printer connected to someone's PC. The system must direct all the files and print jobs to the correct programs and software. Basically, the system layer will take care of all of this, or handle all the sessions in other words. It may also name your system to make the process for the user a lot easier. In general, this layer is important for handling many necessary processes people perform in a network.

Now, on to Layer 6, called the "Presentation" layer. To begin, I am grateful that computers with Mac OS and Windows can communicate with each other despite the many differences, thanks to today's networks. It means less problems for techs, and less interaction of me with Macs (haha.) To summarize what the Presentation layer is meant for, it handles conversion of data into formats that are compatible with a system on the network. This was a problem back then, and it drove many crazy, which is why I say I'm grateful. File formats like PDF were ones that put forth a universally usable document between operating systems. So, this is important for say a Mac to transfer a document to a Windows computer, and for the document to be readable.

Finally, Layer 7! This is the "Application" Layer. Putting this very simply, this part of the network is the most visible one (obviously.) It's pretty much in the name, software applications are very involved in this layer. This is definitely an important part of the OSI Model because you need an application to move files to another computer to begin with! For example, on Windows 7 you have the "Network" application, and I've used it several times before. If you want to go on the internet, well you need a web browser (for sure)! Programs like Google Chrome and Mozilla Firefox specialize in this. To be blunt this layer is mainly for the user. It's hard to believe that this is the 21st Century and people still don't know how to bloody use Windows or Mac OS. Now some applications also have the abilities to encrypt and authenticate data coming and leaving your device. But as we all know these tasks are given to individual applications that only have a certain task. To finally close my analysis of the Application layer, I have to make this clear --- The word "application" in this sense does not refer to the computer applications, just the software that enables the applications to co-operate with the network. This now concludes my lesson on the OSI Model (yay!).

Week 1: Day 003 & Weekend 1: Days 001-002 - MAC Address and NIC + 2nd and 3rd Layer of OSI Model and Some TCP/IP

    So, today I applied/enrolled to NOVA. Funny enough, I don't have to take the Math entry test, due to my Math SOLs. In addition, I might also be exempt from the English entry test if my PSAT score was 50 on Reading and Writing. Anyways, onto what I have learned today.

     Today, I learned a little more about the NIC (Network Interface Card) not all there is though. However, I learned more about the importance and the mechanics of a MAC Address. So, the mac address is built in the NIC as a way to identify the sender/recipients' computer. The first 6 digits represent the manufacturer, and the rest are uniquely given as a serial number. Continuing, the NICs send information known as "frames" to the switches. Each frame has a set amount of data it can carry, and when there is more data than it can carry, then more frames are sent. The way that the data travels to the switch is through binary code which is representative of the electric pulses sent through from A to B. Each of these frames have an FCS (Frame Check Sequence) implemented and that uses CRC (Cyclic Redundancy Check) to make sure the data arrived to its destination intact. So with that said, each NIC connected to the network reads all data in the network. Since only one system can speak at a time in this model, networks use frames to restrict the data an NIC can send at once. But how is an NIC able to identify the NIC to which it is sending data to? Well it usually knows from an earlier communication, but if not it sends a broadcast asking for the name of the other NIC. To summarize the process, the NIC creates the frame, adds the FCS, and of course the data into the said frame, it then inputs the destination MAC Address and its own Mac Address into the frame, then ships the frame (once no other NIC is using the cable) to the switch. The frame then proceeds to transport itself to the switch through the wire. If the receiving NIC sees that the frame is addressed to itself, then it will read it, but if it's not then it erases the frame. So to complete its task, the receiving NIC scans the data with its FCS then sends the data to the software (Network Operating System) to be processed. However the tasks I've just written about are broken down into two jobs. The first is LLC (Logical Link Control). This job require talking to the Network Operating System, placing data into frames (plus the CRCs). In addition, it deals with processing of the incoming frames, discarding the ones addressed to other machines/NICs in the network. The second job is MAC (Media Access Control) and all it does is remember the NICs own MAC Address and attaches MAC Addresses to frames which include sender and recipient. And the MAC job's final task is to send the frame to its destination. The NICs are placed in the Data Link Layer (2nd Layer) of the OSI model (although many students think it should be Physical due to its task of putting binary code into the network cable).

     Now layer 3 is where you get to the real Network nitty gritty. First off, when you have so many MAC Addresses being broadcast how is it organised in a way that wouldn't flood the internet? Well when networks get so large they can't look at the MAC Address anymore, instead another system is used to identify computers/networks known as the "logical addressing method". This gives the ability for networks to be broken up into subnets when they become to large. To use this system a special software must be used, known as the "network protocol". This software gives unique identifiers to each system, and also handles chopped up packets to make sure packets get from one subnet to another. At layer 3 you have Internet Protocol used as the logical addressing protocol for TCP/IP and gives each device a unique identifier known as an IP Address. This differs from the MAC Address because it is a "logical address" rather than a physical one. An IP address is made up of four 8-bit numbers with numbers ranging from 0 to 255. No two devices or systems on a network share the same IP addresses. The router is what connects each of the subnets. Routers use the IP not MAC address to forward data. In a TCP/IP networks to send data successfully, they need to be put in two containers. A frame lets you move data from one device to another and inside is an IP specified container which tells the frame where to go. Now the inner container is the "packet". The IP packets are shipped in an NIC frame and sent to its destination. The data is then received by the router which opens the frame takes the packet and sends it to its destination (possibly a subnet router), in a new frame which is made for whatever type of connection the user has (DSL or Cable). When the packet reaches a subnet router, then that router once again opens the frame then adds another frame with the MAC address of the device with the meant IP address destination. Once it reaches the NIC of the meant destination, it opens the frame and sends the packet to software that knows what to do with it. And that pretty much ends my reading on the first three layers of the OSI model plus my first look at TCP/IP. Took me three days with all the work I'm doing for other classes. Now it's onto the next four which seems to be 20 more pages of reading. Thanks for reading this entry, more to come!

Week 1: Day 002 - OSI Seven Layer Model

Hello, to make up for me not blogging yesterday, this is a second post about my progress (and it's been two days since the start of school). Anyways, today I've been learning about the OSI Seven Layer Model system. Although this is not widely used, it is great to know for a tech, and I would like to try to set up one of these networks at some point. I learned a good acronym to remember the seven layers "Please Do Not Throw Sausage Pizza Away" --- which represents: Physical, Data Link, Network, Transport, Session, Presentation, Application. In the textbook a hypothetical situation was made, where two people needed to exchange data between two PC's. To do this I need several items: UTP Cabling, a hub/switch, and an NIC (Network Interface Card). Tomorrow, I hope to learn how to use these properly in the OSI 7-Layer system. Until tommorow, tschuss (German for "bye")!

Week 1: Day 001 - Welcome to my blog!

Hello to all new readers of my blog (most likely only my teacher haha), this blog will document my journey throughout my school year (around 10 months) in my Advanced Topic in IT class. My main focus will be on Network Management, and as a year long goal, I will try to dual enroll into a NOVA course regarding this area, and go for a Network + Certification to start off. If that works out, then I will see my options for the future. Join me on my long journey, and hopefully we will all learn many things on the way!