Jack Scott's Blog

First of all, the usual warning: I take no responsibility for any harm done to yourself or your equipment if you decide to take my lead and mod the fan on your switch. It’s your fault for listening to some guy on the Internet you’ve never met.

A little while ago I acquired some old 3550 switches from a friend, and I haven’t used them much because they’re horrifically loud. Recently though, I decided to try and make them quiet enough to leave on in the living room. While I didn’t succeed, I made enough of a difference that I thought it might be worth sharing.

Please note that this mod isn’t going to work if your switch is a) under warranty; b) installed in an equipment rack with hot/cold aisles; or c) you don’t like taking the cover off equipment that has 240v inside.

Basically, the gist is this: The fan inside the switch has a cover on it. By removing half of the cover (the half that isn’t attached to the fan motor) and then mounting the fan upside down, you reduce the vibrations of the fan’s casing. Please also note that the outlet fan is thus turned into an intake fan; it takes cold air from the back of the router and blows it over the power supply unit.

The finished fan installation. Much quieter!

Research on the Internet (#cisco on Freenode and some forums) led me to decide that complete removal of the fan wasn’t an option, due to the switch overheating. I then wanted to replace the fan with a quieter computer fan, but the connector, though the same, is wired differently. Though I own (and can operate) a soldering iron, I’m also quite lazy. Turning the fan upside down (as suggested by a friend) was much easier!

Update 2011-08-17: I initially tried this with my non-PoE switch. Today I tried this with my PoE switch and tested it running a few PoE devices. It quickly overheated, so I don’t recommend this with the PoE (inline power) models.

Today, seeing that I haven’t done so for a while now, comes an update on my life.

I’ve just started my second year at university. My degree is supposed to be three years long, but I’ll stretch it out to three and a half because I failed stuff bigger is better. I’m still doing computing. This year comes one of the units I’ve eagerly anticipated: Algorithms. It’s programming in C, finally, after a year of Java. Also comes a not-so anticipated unit, ICT Project Management. It’s as dull as it sounds.

I’m not really sure why I’m at university. Mostly just because I can’t figure out anything else worth doing. I could go get a job, but having done that before, university seems much easier. I enjoy playing around with computers and programming, but I’m not quite confident that I really want a job as a programmer… I should probably figure that out soonish.

After resigning from Principal Computers again before I left to move to Berlin in July last year (which I ended up not doing, sadly enough), I’m now back there working Saturdays again. And I still jump every time the phone rings. Talk about Pavlov’s dog.

I’ve started playing around with Cisco networking gear again. This time I’ve got a 3550 switch, which strangely enough is more of a 24-port router than a switch. It can do some weird and wonderful things. I can’t wait to do the networking unit at university.

Over the Christmas/New Year period, I was simultaneously browsing eBay for junk and trying to come up with some more stuff to stick in my server rack, which I had just finished moving under my house (picture of it here). A very dangerous combination. After a small delay of contemplation into which model I should get, I ended up buying a Cisco 2610 router second hand. I hope to achieve a few things with this purchase:

1. Firstly, I want to learn to configure Cisco routers properly, with the goal of some day in the distant future getting a CCNA qualification.
2. Secondly, I needed to fill some more space in my rack.
3. I wanted a modem/router near my server. At the moment my server is connected to the Internet via a wireless connection to a modem at the other end of the house.

I received the router in the mail yesterday, and I was a bit dissapointed. Unfortunately the front bezel had come off, which was a bit annoying. I can glue it back on though, and it’s only a cosmetic thing anyway. Far more important is that they hadn’t shipped it with rack ears, which is one of three reasons I bought it. I sent an email off, and a set of rack ears is on its way.

To make the router useful, you can add any number of different cards (such as for ISDN, ADSL, T1, and so on). Cisco calls these things WICs, for WAN Interface Card. I had to buy an ADSL one. It cost twice as much as the router did, because the ADSL WIC is still used in production, where the router is end-of-life. I also bought an external 56k dialup modem, so that I can set up a backup Internet service (which hopefully will autotomatically switch over) in case my ADSL line drops out (which it does once every three years, for about an hour).

At the moment I’m still waiting on a console cable to connect the router to my PC for the initial configuration. Once I’ve got that, I’ll get stuck into the configuration, and hopefully not blow anything up too badly…