Chapter 7: WANs and remote connectivity

Chapter 7 covered WANs, or Wide Area Networks. A WAN is a network that spans more than one site. My current employer has a WAN running some proprietary software that spans all of the stores in the company that we use for internal communication and day-to-day operations. WANs have their own topologies, in this case based on sites rather than nodes. Bus, ring, and star are present just like in LANs, and they mean roughly the same thing. A bus is a network where each site is connected to no more than two other sites in a line, a ring is similar to a bus, but the “ends” meet, and a star configuration has a central site to which the others connect. There are also mesh topologies (all the sites are directly connected to each other – high performance and fail safe, but very expensive) and a tiered topology (basically connect several star networks in bus configuration – the central sites basically function as the network's backbone).

The chapter covered the use of PSTN (Public Switched Telephone Network) or, more humorously and appropriately POTS (Plain Old Telephone Service) and its utility in data transmission. As it turns out, there are a number of different ways to get data over phone lines. You've got old, slow, crummy, sad dial-up service, which is about as useful in today's age as a handcart is for moving a battleship. (Then again, it's still better than carrying the battleship by hand...) There's ISDN which is slow and expensive (and not very common, either). There's DSL which is actually pretty nice if you get a high-throughput plan. And then there are T-lines, which used to be the fastest available, but are now getting serious competition from DSL. If you're able to read these words, you know speed is good where data transmission is concerned.

The chapter also covered SONET, a high-speed dual-ring network setup (one going clockwise, the other counterclockwise) over fiber-optic cable. It's exceedingly fault-tolerant and it's also very expensive. The most interesting thing about SONET to me, though, is that there's still a viable use for a ring-topology network in today's world.

Finally, the chapter covered remote access, touching on dial-up networking, remote access servers, and VPNs. The application of these technologies in the real world is obvious – most business travelers now own laptops for the express purpose of being able to access data back at their home office. VPNs also have the additional handy feature of allowing greater security at a public hotspot if used to connect to a more secure system.

I got a kick out of this chapter – I just think it's cool that the old ring topology is still useful in today's world, and reading about the different types of WAN technology was a fun walk down memory lane.