Are You Connected?

Fellow CSSrs certainly were as they got hands-on experience understanding networking with Network Security Engineers Renne Mings and David Smith. Their presentation outlined the key components to networking; the OSI model, networking communication, networking equipment, network connectivity and network troubleshooting tools. By the end of it, all students were given a demonstration of how to create VLANs and trunk ports.

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CSSrs engaged in the networking presentation.

The beginning moments of the session were a matter of checking in with the knowledge of students starting with the OSI model. Although many would like to think that the OSI Model is not a significant concept to know outside of Computer Science theory, Mings and Smith certainly felt otherwise. According to the SANS Institute, the Open Systems Interconnection model is “a hierarchical architecture that logically partitions the functions required to support system-to-system communication” (2). Anything that deals with networking according to Mings and Smith is grounded by the OSI Model or a variant of it. Put simply, it is the foundation upon which networking is built.  For those who do not know, the OSI model consists of 7 layers.

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Smith explained that the first layer of the OSI was the Physical layer.  The function of the second layer or the Data Link layer was to handle possible collisions on the networks. The third layer or the Network layer dealt with connecting the networks, and the IP Packets were broken down into Ethernet frames and placed on the wire. With the fourth layer or the Transport layer, its responsibility was to transport packets. Smith added that the three-way handshake occurred within this layer. The fifth layer or the Session layer comprised of UDP packets. The sixth layer known as the Presentation layer relays an interface which allows the user to view the communication at hand. Finally, with the seventh layer or the Application layer, it is just that; the ‘app’ itself, which is anything like Facebook or Instagram.  Emphasis was placed on the fact that if any one layer ceased to work then nothing would work.  (For a more in-depth synopsis and description of what each layer’s function is you can click this link: https://support.microsoft.com/en-us/kb/103884) In a technician’s day-to-day, knowing each layer and its functionality is compulsory.

Once the importance of the OSI model was established, Mings and Smith moved onto IT networks. After much insistence from the presenters, some students of CSS finally gave their definition of what an IT network was, which in essence, was a collection of computers communicating with each other.  Both presenters then clarified what was Network Communication.

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Some types of Network Communication.

Subsequently, they quizzed students on the types of IP addresses there were. The President of CSS accurately responded that there were two types;  IPV4 and IPV6. On the topic of Network Communication, special attention was paid to VLANs and the presenters gave a definition, that is, a VLAN is a group of LANs which exist in the same environment. VLANs as they pertain to the OSI model, works within the second layer or the Data Link layer. Although the ’V’ in VLAN stands for ‘virtual’, Mings and Smith strongly advised that the word should not be taken too literally, as it would create confusion when dealing with VLANs in the real-world. Mings went further in-depth to explain that tags are placed in the IP header so that each tag with the same corresponding ID received the packet. Moreover, the difference between a trunk and an access port is that a trunk carries multiple ports while an access port only carries one.

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Presenter David Smith explaining VLANs.

The presenters then moved onto Networking Equipment which included hubs, switches and routers. In regards to routers, Smith outlined that on the Cave Hill campus, there were two currently available. Smith then specified a number of items which could disrupt wireless connections. Interestingly, microwaves, cordless phones and Bluetooth were among the few things which can overlap with each other and create noise within the wireless connection.

Default gateways were then the topic of discussion. Mings contended that the default gateway allows an established connection with other IP addresses outside of the current domain. It is usually placed at the beginning or the end of a subnet mask. Without this default gateway, it is impossible to establish communication. A demonstration of the troubleshooting tool Traceroute went underway with the utilisation of a program called Visual Route. Although Mings outlined a number of network troubleshooting tools, he specified that Wire Shark was a very useful one that helps in understanding troubleshooting in networks.

After showing the club MTJR connectors, Mings connected to the switch and made configurations to four computers on two different VLANs so that they could communicate with each other. He also assigned each VLAN with an IP address. Finally he created a trunk port and displayed the interface and all of this was done using the command prompt. However, once everything was up and running, Mings and Smith encountered problems when testing the VLANs. This prompted Mings to use the ping command to test one of the computers connected to the switch. He then used the trace route command, then the path ping command to determine whether there was any packet loss on the network and Netstat was used to view all available ports.

Unfortunately, the session had to come to a conclusion before the problem with the VLANs could be solved. Ultimately, however, CSSrs were more than appreciative for the demonstration as well as the general information given during the presentation. One person even commented that the session was significantly more helpful than the Networks course he had taken the previous semester. It certainly is a shame if any Computer Science students or persons interested in Technology for that matter, missed such an informative and brilliant presentation. However, whether you’re a part of the CSS team already or a visitor who stumbled upon the site, we do encourage you to check out our Events page so you never have to miss out on such a fulfilling opportunity such as this one.

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