Blog Posts in July 2022

Twilight Zone: File Transfer Never Completes

Ages ago when we were building networks using super-expensive 64kbps WAN links, a customer sent us a weird bug report:

Everything works fine, but we cannot transfer one particular file between two locations – the file transfer stalls and eventually times out. At the same time, we’re seeing increased number of CRC errors on the WAN link.

My chat with the engineer handling the ticket went along these lines:

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Worth Exploring: Akvorado Flow Collector and Visualizer

The results you can get when you know how to apply proper glue to a bunch of open-source tools never cease to amaze me. The latest entrant in that category: Akvorado, a Netflow/IPFIX collector and analyzer by Vincent Bernat.

Some of the sample graphs (shown in the GitHub repo) are not far off from those that knocked our socks off during the first Kentik Networking Field Day presentation. Definitely a tool worth exploring ;)

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Twilight Zone: File Transfer Causes Link Drop

Long long time ago, we built a multi-protocol WAN network for a large organization. Everything worked great, until we got the weirdest bug report I’ve seen thus far:

When trying to transfer a particular file with DECnet to the central location, the WAN link drops. That does not happen with any other file, or when transferring the same file with TCP/IP. The only way to recover is to power cycle the modem.

Try to figure out what was going on before reading any further ;)

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Worth Reading: On the Dangers of Cryptocurrencies...

Bruce Schneier wrote an article on the dangers of cryptocurrencies and the uselessness of blockchain, including this gem:

From its inception, this technology has been a solution in search of a problem and has now latched onto concepts such as financial inclusion and data transparency to justify its existence, despite far better solutions to these issues already in use.

Please feel free to tell me how he’s just another individual full of misguided opinions… after all, what does he know about crypto?

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