Shabby chic for network engineers

I’ll let you into a little secret: when you have a network engineer in who starts taking everything to bits, there’s a very simple way to evaluate how good he is. Look at his laptop: if it’s shiny, new and adorned with all manner of wireless antennas, webcams and the like, then he probably isn’t quite as au fait as the guy who carries something battered and scratched from the 1990s in the boot of his car.

Shabby chic for network engineers

Naturally, I wouldn’t propose this as a reliable benchmark were I not capable of achieving a passing grade myself. Only last week, while fiddling with various switches, I hauled out my personal laptop of last resort, a Toshiba Tecra 8000. While waiting for its venerable hard drive to spin up and its familiar and haunting angle-grinder sound effect to fill the room, I realised that this wretched instrument isn’t far short of its 12th birthday.

Pretty much every serious network person has a machine such as this: a laptop that still has the well-proven RS232 serial connector on its backplate, a sturdy port that doesn’t try to be clever or present itself via additional dongles, nappies, adapters or other superfluous add-ons that can be lost, broken (or, in the worst-case scenario, may snap the port itself off the edge of the motherboard).

Toshiba Tecra

Much of the core networking kit still needs to be initially configured via a serial communications port, where you stick a nine-pin serial lead – of the right gender/pin-out – into a laptop running HyperTerminal, then choose a baud rate (if you can remember what one of those is) and watch the network switch through this connection as it starts up.

If you’re very wise or incredibly lucky with your choice of cable, baud setting, laptop and terminal software, then it’s easy-peasy. The switch will start to show you something complicated, intimidatingly important-looking, utterly devoid of clues, graphical niceties or anything redolent of the modern world of Twitter, smartphones and Flash animation.

Lucky numbers

That old aphorism concerning luck – “the more I practise, the luckier I get” – applies in spades to the network wrangler’s choice of laptop. Far too many machines can’t keep up quick conversations with a serial host, and lots more simply refuse to comply with the more arcane settings regarding flow control, nor can they correctly manage a flow control event when one crops up.

This is all a strong argument for sticking with an old machine that was built back when serial ports still mattered to other people besides network wranglers. I’ve found only one recent exception to this rule that’s worth mentioning, and that’s HP’s nc6320. This machine is new enough to have a high-resolution screen and a fast processor, but old enough to have a serial port tucked away at the back of the right-hand side of its case. So far it has talked to everything that my old Toshiba talks to, and I can get a seven-hour battery life using the HP nc6000-series clip-on travel battery.

This is the aspect of networking that causes my inbox to fill up quicker than any other. People who are sufficiently confident to cross-compile millions of lines of source code, or to re-analyse terabytes of SQL data, will collapse into a quivering heap when presented with the blurb that accompanies the typical network switch. It’s an arcane business, they insist, and no sensible information systems worker should have to struggle with any of this stuff. I’ve recently been having an online spat with a group of guys who were absolutely certain that the best possible strategy towards modern networking gear is to leave it all well alone. There’s nothing left to fiddle with, they maintained, which means that there’s nothing left to go wrong.

If that assertion holds water, explain why, after I received a new Netgear GS724TR and plugged a Netgear ReadyNAS NV+ into it, my very first experimental changes to the switch configuration resulted in the rate at which data came off that humble NAS box doubling at a stroke? Yes, you read that right: a few minutes with my trusty and wizened laptop resulted in file-copying speeds jumping from 12Mbits/sec to 30Mbits/sec, and it made even more substantial gains for my project of the day down in the basement, because before the change that machine would crash, while after the change it ran perfectly.

This crucial alteration – which I made by plugging in my old laptop and signing in to the GS724TR’s management interface at its default IP address and subnet – was merely to turn on Flow Control (FC). This is an area of the Ethernet specification that falls under the heading of “features that manufacturers still argue about”. It’s simple enough to describe FC as allowing a device to request that the flow of packets to it be stopped, and that such a request passes through all intervening switches right back to the originator.

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