Teaching Network Infrastructure: Concepts, Strategies, and Techniques ????

Introduction:?

The purpose of this article is to share my experience as a teacher in a technical course on network infrastructure, specifically in the field of network interconnection. I intend to discuss the development of the educational materials I created, as well as pedagogical and technical concepts and practices. The content of this course covers network topology, architecture, and communication protocols for computer networks. From a more specific perspective, it includes protocols, technical documentation, and standards for various layers, such as the physical layer and protocols like ICMP. It also covers the use of commands and techniques like Ping, Tracert, Telnet, and SSH.?

Additionally, it delves into CISCO devices that implement network interconnection, such as switches, specific physical layer ports like PoE technologies and QoS, and concepts of IP routing, CIDR, VLSM, and the differences between static and dynamic routing, as well as RIP, IGRP, EIGRP, OSPF, and BGP protocols. After the theoretical concepts, I will present tools like WireShark, Zabbix, Nagios, and NetFlow. Finally, the article explores CISCO labs for simulated training on the practical application of the theoretical concepts covered.

Pedagogical Strategy:?

In addition to following the pedagogical strategies of the brazilian educational institution where I taught, I enhanced the course with additional resources to provide a strong theoretical foundation and accessible practices for the students. The classes were conducted in 2017, and it is important to consider this timeframe when analyzing the strategies I adopted, as well as the physical limitations that were present at that time.

The institution itself had a module and syllabus, which were presented to the students. My idea was to follow the syllabus while creating new materials that incorporated citations from books and literature available through the institution’s library. I also included scientific articles that reflected academic concepts and experiments related to the course content, as well as official normative documentation from institutions such as IEEE and CISCO, and RFC standards for each protocol in the syllabus. The reference book used, titled “Computer Networking: A Top-Down Approach,” 7th ed., J.F. Kurose and K.W. Ross, included labs with Wireshark software at the end of each chapter, which I utilized throughout the covered topics.

To better illustrate the theoretical concepts, I shared YouTube videos with the class featuring renowned professionals in the infrastructure field. For each class, I prepared a well-defined lesson plan with allocated time for the presentation and discussion of each content. At the end of each class, I provided a written activity to reinforce the theoretical concepts and a simulated practical activity to further strengthen the application of the content covered. All digital teaching materials were made available on Google Drive for the students to preview the content of each class.

On the first day of class, I presented my course plan, based on the institution’s guidelines, with a schedule of classes, competence units, general objectives of the discipline, technical skills, theoretical knowledge, software used, bibliography, and links to important content related to the discipline, including concepts, abbreviations, datasheets, YouTube videos, and CISCO forums where external individuals could engage in relevant discussions and ask questions.

Additionally, on the second day, I conducted a self-assessment questionnaire using Google Forms to measure each student’s prior knowledge level. This allowed for a comparison between their knowledge before and after the course. I carefully selected a scale that did not have a middle response, providing students with four options to better position themselves within the presented scale:

Using this self-assessment questionnaire, I generated comparative graphs to understand how comfortable the students were with the concepts on the first and last day of class st the end. I will make a comparison at the end of this article, presenting my conclusions about the application of the adopted techniques:

Module, Concepts, and Techniques:

1. Basic Network?Concept:

The concept of networks goes beyond the idea of computer networks. To have a network, we need objects connected to each other in some way. If these objects are microprocessed devices, then we have telecommunications networks with devices such as desktop PCs, laptops, smartphones, smartwatches, interconnection equipment like switches, routers, hubs, modems, and access points. Regarding the physical aspect and organization of these devices in the network, we can evaluate the network topology, which can be star, ring, or bus. Not only can we analyze a network architecture considering communication protocols, but we also dive into a soup of acronyms that we will explore more carefully later on.

2. Physical Layer?Testing:?

Usually, in a network infrastructure project, after setting up the physical part and configuring the logic, we perform tests to ensure communication. Regarding the physical layer, we have some tests such as PING, which is the sending of packets to test connectivity between devices (ICND2 2016, pg. 135). The PING command uses the ICMP (Internet Control Message Protocol), defined by RFC 792 With this command, it is possible to send packets, wait, and calculate their response time (ICND2 2008, pg. 195) (Kurose 2010, pg. 262).

As for the Tracert command, used to trace the route of an IP packet, we can use it to identify any errors in the network. In a project where we have knowledge about the network architecture, we simply give the tracert command to check the route between two terminals and determine where it may have stopped. You can see an example in the article below (ISDN2 2016, pg. 145).

Telnet is a network protocol used for remote terminal access in a TCP (Transmission Control Protocol) oriented network. The protocol specifications for Telnet can be found in RFC 854. You can get a better understanding of how it works in (ICND1 2013, pg. 211).

3. Datasheets:

Datasheets are technical documents that provide specifications, operating recommendations, and configuration details for network equipment such as routers, switches, and access points, which are considered interconnection devices. To find datasheets, for example, for CISCO devices, you can visit the website www.cisco.com and search for the desired device. In the datasheet, we can find important information, and we will explore each one related to the Cisco equipment from the 110 series. Let’s take a look at the first part (title) in the datasheet:

In the title, we can identify two important pieces of information. In red, we have the series to which this equipment belongs, Series 110, and right after that, we have an important characteristic: this switch is unmanaged, which means it cannot be programmed for management activities such as controlling data traffic.

In the above figure, in the subtitle, we can see the equipment category as Small Business, a product line by CISCO for small businesses. These are simpler and more affordable devices, with the information that no configuration is required for the equipment to function (“…with Zero configuration required”).

Just below, we have some highlighted information provided by the manufacturer. In the figure below, we can see some of these related to the CISCO 110 series switches.

We can see that the operating speed of the equipment is 10, 100, or 1000 Mbps (Megabits per second). This means that, depending on the device connected to it, it can achieve high data traffic speeds. The next information tells us that within the 110 series, we can acquire equipment with 5 to 24 input ports. These ports can also be used for Power over Ethernet (PoE) to power devices that support it. PoE allows electrical power to be supplied over a wired Ethernet connection. In the last topic, it is emphasized once again that this equipment is plug and play, meaning it works by simply connecting it.

In the next section, we will see a product summary called Overview, presented in the figure below.

We can highlight in the summary the emphasis on low-cost equipment, no configuration required, with guaranteed connectivity (Fast Ethernet and Gigabit Ethernet), reliability, and scalability, meaning it supports network expansion. The highlights at the end are low power consumption, quality of service (QoS), which ensures reduced signal delay variation, sensitivity, and increased product performance to meet quality requirements. In this topic, we also have information that this product has network loop detection, meaning if a cable is directly connected to two ports of the switch, which can severely reduce data traffic speed, the equipment will identify it. It also has cable diagnostics to determine if the cable is functioning properly or has physical damage.

Now let’s look at the equipment characteristics, just below the summary in the figures below:

In the first part of the characteristics, we can see emphasis once again on the fact that this equipment does not require configuration. The data transmission mode, half or full-duplex, is automatic, meaning it can be unilateral or bilateral transmission depending on the case. It supports speeds of 10/100 Mbps or 1 Gbps with automatic cable detection, as well as PoE on Mega and Giga ports, as seen in the figure below:

Regarding the second part of the equipment characteristics, we can see that there is a highlight for support of the IEEE 802.3az standard. In terms of technology support, we have QoS services that support delay-sensitive services, loop detection, cable diagnostics, packet damage identification, and finally, a lifetime hardware warranty.

Now let’s move on to the specification table below in the figure below:

In the specifications, we can see information about the standards the device complies with, IEEE standards, cable types (Category 5 or higher), LED indicators, and interface information such as port speeds and supported voltage for each model in the series. In the last item of the previous figure, we have the dimensions of each equipment in the series (height, width, and length).

In the second part of the specifications, we have information about the weight of each equipment in the series, as well as the type of connection port for each. To learn more about connector types, you can read the document produced by CISCO on the subject, provided below.

In the previous figure, we can identify information about the number of ports with PoE support and the maximum power that can be supplied for each equipment in the series. It can be stated that none of these equipment have cooling fans. As for performance, we can see the maximum data traffic capacity considering all ports in each equipment in bits per second and in millions of 64-byte packets per second.

In the fourth part of the datasheet, we can evaluate the capabilities of the aforementioned features, mounting options, where we can have rack switches, which are support boxes where we assemble the network equipment. In addition to these, we can see the ideal operating temperature and humidity of the equipment, system memory (RAM and Flash), the items that come in the package, which in our case is the switch, a power adapter, quick start guide, and the hardware mounting structure. We can identify the minimum requirements for operation and finally, the warranty, which in this case is a lifetime warranty.

4. Protocols

4.1 IP?Routing:

?The IP address can be compared to the sender and recipient addresses on a letter. Since we are dealing with digital packets on the network, in our case, it is a datagram, and the IP address is the logical address. Since the internet is a network of multiple interconnected physical networks, there is a need to create a route for logical addresses through which the packet will pass until it reaches the recipient, going through gateways of these networks and receiving labels with the IP addresses of each stage of the transmission.

4.2?. CIDR/VLSM:?

CIDR (Classless Inter-Domain Routing) is a subdivision of IP classes that allows flexibility in dividing IP addresses into different networks (ICND2 2008, pg. 396). VLSM (Variable Length Subnet Masking) is when we divide subnets into smaller subnets for better utilization of IP distribution, meaning we make the subnet division variable in relation to the subnet mask (ICND2 2016, pg. 172). For a better understanding, see the explanation and example in the link provided.(ICND2 2008, pg. 145) e (ICND1 2013, pg. 335)

4.3. Static/Dynamic Routing:?

Routing can be done statically, where the routing table in the routers is manually configured and remains unchanged, or it can be done dynamically, where the routes are updated in an attempt to optimize the programmed routes.(ICND2 2008 — pg. 117) e (ICND1 2013 — pg. 517)

4.4. RIP:?

Routing Information Protocol is a protocol for exchanging information between gateways, allowing hosts from one network to communicate with hosts from another. You can see how to configure it practically in the video provided.(ICND1 2013, pg. 530) (Kurose 2010, pg. 285)

4.5. IGRP:?

Interior Gateway Routing Protocol is a proprietary Cisco protocol used to decide the route for packet delivery in the network. You can refer to the official documentation on the Cisco website and watch a video demonstrating its practical application in a simulator.

4.6. EIGRP:?

Enhanced Interior Gateway Routing Protocol is an advanced distance vector routing protocol. It is proprietary to Cisco and is an evolution of the IGRP protocol. The main modification lies in the route planning algorithm, which takes into account factors for large-scale networks.(ICND2 2008, pg. 273) e (ICND2 2016, pg. 265)

4.7. OSPF:?

Open Shortest Path First is a routing protocol for IP networks, created by the IETF (Internet Engineering Task Force) according to RFC 1131.(ICND2 2008, pg.249) e (ICND2 2016, pg. 229) (Kurose 2010, pg. 288)

4.8. BGP:?

Border Gateway Protocol is a dynamic routing protocol for inter-domain routing. It is used in major internet routers and is typically utilized in autonomous systems (AS).(Kurose 2010, pg. 290)

5. Software and?Tools:?

We will use WireShark as a packet analyzer and network traffic monitoring tool, and Zabix, Nagios, or NetFlow as management tools(ICND2 2016, pg. 568). It is necessary to have a better understanding of the Cisco layer concepts when reading this module.

6. Final Considerations:

If you have any doubts about any acronyms or concepts presented in the course, please refer to the dictionary of theoretical concepts. All images in this module were obtained from the pixabay repository.

7. LAB?CISCO:

LAB CISCO 1

Software: Cisco Packet Tracer

Reference: Lab02 of book: “Laboratórios de tecnologia CISCO”, 2012 pg. 41–48

Title: Static routing configuration

LAB CISCO 2

Software: Cisco Packet Tracer

Reference: Lab03 of book: “Laboratórios de tecnologia CISCO", 2012, pg. 49–59

Title: Dynamic routing configuration (RIP, EIGRP, OSPF)

LAB CISCO 3

Software: Cisco Packet Tracer

Reference: Lab04 of book: “Laboratórios de tecnologia CISCO", 2012, pg. 60–66

Title: Route redistribution configuration (EIGRP, OSPF)

LAB CISCO 4

Software: Cisco Packet Tracer

Reference: Lab05 of book: “Laboratórios de tecnologia CISCO", 2012, pg. 67–76

Title: IPV6 routing configuration (static and dynamic — RIP, EIGRP, OSPF)

LAB CISCO 5

Software: GNS3

Reference: Lab22 of book: “Laboratórios de tecnologia CISCO", 2012, pg. 177–182

Title: Advanced routing using OSPF

LAB CISCO 6

Software: GNS3

Reference: Lab30 of book: “Laboratórios de tecnologia CISCO", 2012, pg. 233–238

Title: External routing via BGP

Conclusion:

After applying pedagogical techniques combined with technical content on network interconnection, the class took a test using Google Forms. At the end of the course, they completed a self-evaluation questionnaire so that I could measure their performance before and after applying the techniques. What was lacking in this pedagogical experiment was a control group where more conservative techniques were applied, allowing us to measure the effect of the difference between the techniques I used compared to a class that received a different didactic approach. Therefore, consider the data below only as a non-scientific experiment that measures the effect of the mentioned techniques without a comparative group. I divided the class’s performance results into two forms: a satisfaction form and a self-evaluation form.

Satisfaction form:?

The responses are on a scale of 0 to 3, where 0 means needs improvement and 3 means excellent.

• Regarding the content of the course, 100% of the students found it above average, with 76.5% rating it as excellent:

• In terms of the time needed to cover all the content, the class was divided in half.

• Concerning the teaching resources, only 1 student said it needed improvement, while 58.8% said it was excellent.

• Regarding the pedagogical strategy, 47.1% considered it excellent.

Self-evaluation form:?

In this form, I grouped the responses with values 0, 1, 2, 3, where 0 represents “I don’t know anything” and 3 represents “I master the subject.”

?I compared the results before and after the classes: Comparatively, we can observe that the percentage of students who considered themselves unsure about the content decreased from 27.4% to 9.3% for some questions, showing a difference of 18.1%. On the other hand, the percentage of students who claimed to master the subject increased from 22.4% to 45%, with a difference of 22.6%.

I hope that the teaching practices mentioned in this article can help other professionals in the field of technology education improve the performance of our students. Please comment below on other techniques you have applied and believe can contribute to our technology education community.

References:

• BRITO, Samuel Henrique Bucke. Laboratórios de tecnologias Cisco em infraestrutura de redes. Novatec Editora, 2019.
• KUROSE, James F.; ROSS, Keith W. Computer networking: A top-down approach edition. Addision Wesley, 2007.
• ODOM, Wendell. CCNA Routing and Switching ICND2 200–105 Official Cert Guide. Cisco Press, 2016.
• ODOM, Wendell. CCNA Routing and Switching 200–120 Official Cert Guide Library. 2013.