Computer Networks
August 1, 2017
I absolutely loved this book! It offered for me a much needed soft but detailed introduction into how the internet works. As a coder, as soon as you want to code anything that accesses the internet, understanding the content laid out in this book is essential.
The major narrative in this book I would say is transmission. Building on this the main themes I would say are what do we need to make transmission possible? followed up with how do we then go about making transmission possible? To this end then, the plot ends up being a layer cake: Protocol layers of communication. The first two chapters deal with the ability to transmit, while the remainder deals with how best to transmit.
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I found this text to be very logically organized, and just as importantly, it lets you see the technical details of how to build an internet but without boring you. As a reference, it offers enough of the landscape to get you started.
Some of the application layer stuff is beginning to be dated, and the security and ethics are definitely dated given how much the world wide web has changed, but otherwise I found this book to be very relevant for any coder wanting to write apps that use the internet—which is pretty much everyone these days.
Chapter 1 - Physical Layer
This chapter was interesting in the various transmission hardware it explained. Even in day to day life, society still offers many details about how our technologies work, but I find there's very little when it comes to the hardware infrastructure that makes the internet possible. I think I saw a TEDtalk once. That's about it.
I especially liked the engineering concepts introduced. I come from a math background, not an engineering background, so things like multiplexing I found conceptually fascinating!
Chapter 2 - Data Link Layer
This chapter was more theoretical. Knowing the available hardware from the previous chapter, we're taken to looking at how to make transmissions across such hardware reliable. I enjoyed the practical considerations as this chapter still split up the discussion making good comparisons between physical and wireless connectivity. At the end of the day though, it was more about error correction, as well as sustainable transmission—which is to say smoothly paced and synchronous transmissions, for example.
Chapter 3 - Medium Access Control Layer
My favorite part of this chapter is finding out what MAC means, and how it applies to the internet. Mostly because everytime I booted up a computer when I was originally attending school, the screen always mentioned a "MAC Address" and I always wondered what that was, haha.
That's exactly it though. With the potential of transmission discussed in the previous two chapters, we finally get to take a look at an actual end to end transmission. As this is an engineer's book, we mitigate complexity through stratification. This is the first layer beyond the physical, and is the simplest. This chapter focuses on local transmission from device to device within a single network, each device having its own identifiable MAC address.
Chapter 4 - Network Layer
The network layer is where things finally start coming together. It's the IP layer, the Internet Protocol. As a programmer, I've written a few applications which make use of the internet protocol. Mostly I was relying on libraries which had good enough documentation that I managed to succeed with my code, but I only kind of knew what I was doing.
I'm not saying this is the preferred approach, but when you're self-taught it's also difficult sometimes to find comprehensive material to teach how an entire technology stack works. I am absolutely grateful to this book, and this chapter in particular as it illuminated so many words I had come across previously such as packets, routing, traffic, control, shaping, IPv4, IPv6. Many of these concepts I had intuitive understandings, enough to get by, but it's so much more satisfying to find something definitive.
Chapter 5 - Transport Layer
In a way, you can consider the network layer an explanation of the capability of transmission, as it laid down the IP infrastructure. In that case, the transport layer explores how to go about transmitting at this level of complexity. In particular, this is where one learns about things like sockets, connection establishments, connection releases, error correction.
The other valuable knowledge this chapter introduces is that there are two transport layer protocols: Transmission Control Protocol (TCP) as well as User Datagram Protocol (UDP). I never knew there were two ways to send a message across the internet.
Chapter 6 - Application Layer
For me, the most useful part of this chapter was in understanding how the Domain Name System (DNS) works. I've run into the term, especially in learning to use linux, but it was kinda vague until now. I definitely found understanding this layer worthwhile, as it helped clarify to me how applications use ports, and how uniform resource locators (urls) actually work.
So much of the internet is just done for us, we don't even question it, so it's nice to see the processes behind these things.
Chapter 7 - Security and Ethics
This was the one layer that didn't fit the narrative, or rather the mitigation strategy. In a way, security and ethics are orthogonal considerations, but I tend to agree with the general assessment given in this chapter that security needs to be interleaved within this layer cake, it needs to exist within each protocol in the technology stack. My only criticism—not just for this book but for this and so many others—is that security is always an after-thought. Then again, many of the books I've read were written long before this newer more dangerous internet. The threat vectors of the day were immature in comparison to what needs to be taken into account today.