Network Engineering and Administration
Posted on August 19, 2008 by Jonathan Carr |
I. What is Networking?
A single computer with a decent set of productivity tools (word processing, spreadsheets, relational databases, etc.) is capable of increasing the productivity of a human being. Given that the whole is greater than the sum of its parts, networking computers together can increase the productivity of all aspects contained within a professional organization. Networking is the concept of sharing computer resources over a network medium (wired or wireless). Such a concept is responsible for sparking the internet as we know it today. In the late 1960’s a group of universities tried out this idea and it was so successful that the Department of Defense used the methodology to create an indestructible communications network which could remain active even under a severe nuclear strike on our country. This was an amazing advancement from sneakernet (saving to a disk and walking the data to another computer). Up until the early 1990’s this network was only capable of transferring data in the form of text from one computer to another. Then something happened. It became possible to also transfer images, video, sound, and hypertext links. This was the birth of the world wide web (WWW). The world wide web is a term that can be used interchangeably today with the term internet. You could say that the world wide web was the expansion of the internet into the hands of the global public, however, today they are virtually the same thing. In the mid-to-late 1990’s, animation and greater interactivity became possible on the internet, thanks to the high-level object-oriented programming language called Java. It then became possible to implement input/processing/output on a web page which allowed people to shop online. You know this as e-Commerce. After the millennium, a new generation of the internet was born (web 2.0) thanks to web technologies such as collaborative authoring (wikis), social networking (blogs), syndication (RSS feeds), and many open-source methodologies. Here we sit today, with the internet inter-twined in our daily routines and rituals.
Getting back to networking, organizations have found it possible to create mini-internets withing their infrastructure. These mini-internets act and behave just like the world wide web visible through a web browser. They are called intranets and they are made possible only through networking. An intranet can connect executive administration, accounting, operations, marketing, sales, human resources and many other aspects of business together while remaining private to the outside world. Sometimes, an intranet must be accessible to someone who is at home and not in the office. A virtual private network (VPN) can be set up for this and allow employees to telecommute. This is called an extranet. An extranet is like an intranet in the sense that only authorized users of an organization can access it, however, it can use the internet to reach employees who are off the physical campus of an organization. It can be confusing to grasp the concepts of internet, intranet, and extranet, but you can clearly see how each offers unique advantages to the current world of business.
With the current networking technology in-place, a new type of application has surfaced and quickly made its way into corporations around the planet. Enterprise resource planning (ERP) is a software suite that manages multiple divisions of an organization through a network in a single database. ERP can seamlessly integrate human resources with accounting, marketing with sales, information technology with executive administration, etc. With thousands of employees on different continents accessing multi-user relational databases, network engineers and network administrators are necessary to ensure productive and secure data transfer occurs across such networks. Because of this, networking is now a major part of any information technology department for businesses…small, medium, and large.
II. Voice Communications
Up until the broadband revolution, the only computers that had high speed internet access were client computers of a client/server network (more on that later) with a single main internet connection such as that of ISDN, a T1, or a T3 connection. All telecommunications happened across phone lines. When cable and DSL modems made their way into consumer homes, a new type of voice communications became popular. It became possible to use a high speed internet connection for telephony. The technology is known as Voice Over Internet Protocol (VOIP). VOIP is a less expensive telecommunications option for large corporations with many phone lines. A digital VOIP Private Branch Exchange (PBX) system can really cut costs when properly implemented. VOIP is a great technology and is only made possible by networking. This increases the responsibility of the network engineer/administrator because now they must deal with both data and voice.
The early VOIP implementations were highly scrutinized because they didn’t offer the same Quality of Service (QoS) that standard land-lines offered. Also, there was a lack of features like call waiting, conference calling, call forwarding, etc. with early VOIP. Today, there has been major improvements to QOS and pretty much all features offered with old phone lines are now offered with VOIP. VOIP is transfered over ethernet cable and onto the internet the same way data is, therefore long distance communications cost the same as local calls. This presents a great threat to major telecommunications companies who are based on land line telephony.
III. Protocols
A protocol is best defined as the language spoken on a network, much like English, Spanish, or Chinese. When data leaves point A, it must be compiled into a standard so that it can be interpreted by point B which shares the same standard.
OSI
The International Standards Organization (ISO) created a protocol called the Open Systems Interconnect (OSI) model. There are not any implementations of the OSI because it is just a model framework used to build from. OSI has 7 layers:
7) Application Layer (top layer) - This layer represents the implementation of an application, such as a web browser or email application. It is used for programs specifically written to run over the network. It handles network access, flow control, and error recovery.
6) Presentation Layer - This layer handles encryption and authentication (character conversion, protocol conversion, and data compression)
5) Session Layer - This layer is responsible for confirming that one-on-one communication has been established. Think of when you pull up to the speaker/mic in a fast-food drive through and the teller says, “Can I take your order?”
4) Transport Layer - This layer manages the transmission of information. Think of a train how it is divided into equal train cars. This layer organizes the transportation of the data in a similar way. It provides a blueprint of how the data will be segmented.
3) Network Layer - This layer assigned an address to the data. The previous layer names the data but an address is required for proper connection and transmission. Back to the train analogy, this layer stamps an address on each train car.
2) Data Link Layer - Once a connection is made, the data packets are named, and each packet has an address, this layer allows for the transmission of the data. This is where the actual 1s and 0s travel through the medium. Back to the drive through analogy, this is where the teller hands you your food.
1) Physical Layer (bottom layer) - This layer is visible. It is whatever medium (wired or wireless) used to transmit the data. It can consist of cables, network cards, and network hardware.
The best way to remember the layers of OSI starting from the bottom is: “Please Do Not Throw Sausage Pizza Away”
TCP/IP
TCP/IP is an implementation of the OSI model and it is by far the most commonly used protocol on the internet and within organizations. The TCP/IP protocol only has 5 layers because it combines the application, presentation, and session layers into a single application or process layer. The other layers are mostly the same except the network layer is represented as the IP layer and the data link layer is called the network interface. Like I said, the OSI is a model and the TCP/IP is an implementation of the model.
Some common applications that use TCP/IP are SMTP, FTP, TELNET, and HTTP. On a TCP/IP network, nodes are assigned by 4 octets in the form of: XXX.XXX.XXX.XXX. Each octet tells what type of IP network you are on.
If the first octet is in the range of 1 and 126, you are on a large Class A network. If the first octet is between 128 and 191, then you are on a Class B network. If the first octet is between 192 and 223, then you are on a Class C network. If the first octet is between 224 and 239, then you are on a Class D network. Lastly, if the first octet is between 240 and 255, then you are on a Class E network. By the way, TCP/IP stands for Transmission Control Protocol/Internet Protocol.
IV. Architecture
Network architecture is typically one of three designs or hybrids of the same. First, which is the oldest, is called a ring. A ring network is where all computers are connected to each other with no center-point. Each computer has an input/output and there is no begin/end to the network, just a loop. On this type of network, a computer transmits data which travels around the loop until it reaches its destination computer. Ring networks still exist today, although considered archaic. Some are called token-ring networks because a token is passed around the ring network so that only one computer transmits at a time. There was even an attempt to create a high-speed token-ring model by Cisco Systems, however, ethernet reigned superior.
The second type of network architecture is called a bus. A bus is just like a ring except there is a definite beginning and end. Just think of a horizontal line with 5 computers hooked up to it. Alone, this network type is also out-dated, however, when combined with the next type of network, is very common.
Last but not least is a star network. This is the most commonly used type of network today. A star network is when multiple computers are linked to a centralized location such as a server, hub, switch, router, etc. A branch of a star network can be arranged like a bus as mentioned above. A hub is a port where only two devices can communicate at once through it. A switch is a “smart-hub” where all devices can communicate at the same time. A router is a device that combines a switch with access to a large network such as that of the internet. Star networks make client/server computing a reasonable networking solution for large enterprise-level organizations.
V. Security
Network security has become a big issue amongst all networks. For wired networks, hardware features firewalls and standard information security practices such as software suites (anti-virus, anti-spyware, anti-spam, etc.) and encryption methods like DES, Triple DES, AES, RSA, etc. Wireless security is a different animal in itself. It presents a unique threat from someone within the proximity of the wireless network range. To fight this threat, wireless networks are encrypted within themselves. Wired Equivalent Privacy (WEP) used to be acceptable in the late 1990s, however, it is easy to break through with amateur software now. WEP uses a 40 or 104-bit key. Wi-Fi Protected Access (WPA) was then developed which features a 128-bit key. To this day, there has been no successful WPA hacks, however, enterprise IT professionals look down upon it as there is a better solution. WPA2 is a state-of-the-art wireless encryption method as it features the Advanced Encryption Standard (AES) and it is the standard for enterprise-level applications.
VI. Engineering
Network engineering is the practice of designing a network solution for a real world implementation. There are a few different levels of network engineering. First is a logical design. Just as architects create blue-prints of building designs, a network engineer should do the same for a network. It is sort of an artists sketch of the concepts used within the network. This demonstrates how the network will communicate not only with the hardware on the network, but also with the outside world. A great software tool for this is Microsoft Visio.
After a logical design is agreed upon, the next step is to create a physical design. An architect does this by creating a small scale-model of their design. A network engineer does this by creating a layout of where wires go, where they terminate, what computers are used, etc. After a solid logical and physical design of the network is in-place, next is to actually implement the design. This is where the wires are actually ran through walls and connected to the proper hardware devices. Network software is then configured (which can be Microsoft Server, Unix, device firmware, etc.) and the network becomes operational.
VII. Administration
After a network becomes operational, a network administrator (which can be a network engineer) maintains the network. Sometimes servers must be re-booted, cables go bad, or even the entire network must be re-booted. Sometimes a network is working perfect internally, but isn’t seeing the external internet. A network administrator’s duty is to make sure all systems are operational in this sense. Network engineering and network administration are crucial to any IT department whether it is a small or large organization.
VIII. Wrap Up
I would like to leave you with a video that is worth watching. It illustrates what goes on inside a network. It is called “Warriors of the Net” and it could be the best 13 minutes of your life if you like computer networking. Thanks for stopping by…
VIII. References
Image from Atlas Communications Inc.
Video from TNG Medialab found on YouTube.
Comments
4 Responses to “Network Engineering and Administration”
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Once again- so impressed with your knowledge. On a practical level you were the one who networked the entire yrbk project in ‘98 and put it on a tech level after that! Awsome!
Nice explanation. I remember watching that video in my networking classes.
Ahh, the good old yearbook network…an 8 port hub, six 486 machines, and custom batch files.
Thanks Tim, I saw this video in my telecommunications systems class back in my undergraduate studies.
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