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Network World - Before look at a wide area and network performance analysis tool this week I want to add another language to the list of worthy tools I suggested in Gearhead the week before last.
The first is Erlang, another functional programming language described by Wikipedia as "a general-purpose concurrent, garbage-collected programming language and runtime system."
Developed by Ericsson in 1986 and turned loose as open source in 1998, this language has gathered a lot of adherents and a recent book, "Learn You Some Erlang for Great Good!" by Fred Hebert (pub. No Starch), which is a great place to start exploring the topic.
Herbert says Erlang "is no silver bullet and will be particularly bad at things like image and signal processing, operating system device drivers, and other functions."
So what good is it? Erlang "will shine at things like large software for server use (for example, queue middleware, web servers, real-time bidding and distributed database implementations), doing some lifting coupled with other languages, higher-level protocol implementation, and so on," Herbert writes. "Areas in the middle will depend on you."
According to Wikipedia, in 1998 "the Ericsson AXD301 switch was announced, containing over a million lines of Erlang, and reported to achieve a reliability of nine '9's.'" Impressive.
I've only just started getting into this fascinating language (so many languages, so many books, so little time), but I'm going to give the book a Gearhead rating of 5 out of 5.
By the way, the publisher, No Starch, does something I love ... buy the book and you get a DRM-free ebook copy in ePub, Mobi, or PDF format thrown in.
No Starch recently released another good tome, "The Book of GIMP," which is a great way to learn about what is, in effect, the free, open source alternative to Photoshop called GIMP.
So, on to the main event for this week ...
Monitoring the performance of a network with WAN links is tricky. At the most basic level you want to know how fast data can get from point A on one subnetwork to point B on another subnet and, for that, you might consider using a tool to automatically ping remote nodes.
But while pinging tells you what the transit delay (latency) is from A to B, it doesn't tell you whether the bandwidth you think you should have between A and B is actually there. It also doesn't tell you about how well services such as Voice Over IP (VoIP) might work. Or not work.
A simplistic way to test available bandwidth is to run a load test ... just stop all other use of the link between A and B and upload and download files as fast as you can to see how much data the link can transfer. Voila! You'll have a snapshot of your connection, but it only tells you what things look like at that moment; a minute, an hour, or a day later the connection may not perform as well.
What you really need is a technique that can analyze a network connection in real-time and in-band.
<digression> By the way, what is this irritating habit that has sprung up in the computer industry where things like updates and patches are being described as "in-band" if they are released on a schedule and "out-of-band" it they aren't scheduled? Once again, it appears this linguistic offense can be laid at the feet of Microsoft and, sadly, it seems to have started to spread to the verbiage of all sorts of people and organizations. Mostly marketing types. Sigh.</digression>