Never been one to let the carrier drop

I have a number of criticisms of the current economic system, as many of you know. I pretty much hate money, and think everyone should have access to unlimited resources. Haven’t figured out how to implement that one yet.. 😉

Anyway, one of my criticisms of the stock market is of margin accounts. I have a margin account – I don’t remember what feature I needed that the regular account didn’t offer, but there was something having nothing to do with what I’d normally think of as margin that I couldn’t do unless I switched to a margin account. I’ve purchased on margin a few times, and I’ve had to answer a margin call once. I was able to.. but I’m not criticizing it because of me.

Instead, I’m criticizing it because of the people who can’t make their margin call. Not, as you might think, because I feel sorry for them – although I do – but because I feel sorry for the whole system. It’s *got* to be dynamically unstable.

Here’s the problem. If you can’t answer a margin call, your broker sells off your assets to pay back your margin debt. Now, if this were a isolated system and you were the only user of it, this would work fine. However, you’re *not* the only user – and selling off your assets lowers the price of those assets for everyone else. Maybe only fractions of a penny for each individual margin call – but multiply that by 10,000 or 100,000, and you’re starting to talk about some pretty serious wampum. Now, one side effect of lowering the price of those assets is that it makes other people’s margin ceiling *lower*, because your margin purchasing power is based on the value of the assets you hold. So, it can result in other people getting margin calls – which some of them will be unable to pay – and the result is kind of a domino effect which only starts to be really apparent in a prolonged bear market.

Who would design such a thing? I nominate Bloody Stupid Johnson, from Discworld. It has his flavor to it.

I should mention that I’m not in fact a financial guru, and there might be some really well designed effect that counteracts what I’ve just described. Feel free to comment.

So, I’m here today to tell you about a little adventure that I went on, and perhaps save you some headache if you happen to be trying to go on a similar adventure.

The beginning of our story: recent events caused me to reacquaint myself with Cisco’s layer 5 switches, also known as the Cisco CSS series. These were originally a product called Arrowpoint, made I think by a company of the same name, and when I first started playing with them around my Epoch Internet days, they were horribly expensive.

They’re not any more. You can find them on e-bay for $150-$300. They’re kind of nice, really – they’re capable of being regular layer 2 switches, layer 3 switches, or ‘content aware’ switches – so they can do NAT-style load balancing at wire speeds – as well as doing URL-aware traffic directing – which presumably means speeds approaching a gigabit since most of them have gigabit fiber ports, or at least spots for a fiber transceiver.

But, never mind the sales pitch – I presume if you’re reading this and you found it from Google, it’s because you have one of these things and you’d like to initially configure it, which requires a console cable. NOT, mind you, the standard Cisco blue console cable that we all carry around – nay, nor the 3Com nor Baytech console cables (which are also DB9-RJ45), nor any of the above with a null modem.. nor, amusingly enough, even the Official CSS-CONSOLE-KIT that one might order from any number of vendors and Cisco describes at http://www.cisco.com/en/US/products/hw/contnetw/ps789/products_tech_note09186a00800a3f28.shtml

At the point at which I discovered this – including ordering a $54 CSS-CONSOLE-KIT off ebay and a $74 CSS-CONSOLE-KIT from CablesAndKits.com and finding that neither one worked correctly – I was starting to wonder if I had somehow acquired not one, nor two, but three CSS boxes that didn’t work. It seemed unlikely.

Finally, I got frustrated, and did what I should have done several iterations earlier.. I made two RJ45 pigtails – one I marked TX, RX, and ground on (since it was connecting to a PC port through a standard Cisco console adapter, it was a known quantity) and the other one.. first I determined which pin was ground – pretty easy, just set voltmeter on continuity and measure with CSS turned off between CSS frame and pins. Then, I turned on the CSS and measured voltage between ground and various pins – it didn’t take long to determine that there were just two pins that were floating – one of which had to be RX. There were also only a couple of pins which had approximately the right voltage to be transmitting data. I toggled the power on the CSS while connecting each of them to RX on the PC – and before long, I had found my transmit pin. From there, finding my receive pin was just a matter of trying all the possibilities until something made the box start responding when I hit keys.

To get the resulting pinout, please paypal $5 to sheer@sheer.us… just kidding.

Seriously, the pinout is as follows:

 Terminal side            CSS side

3                                   2

6                                  3

5                                   1

Hopefully this information will save you some time.

To clarify, this pinout is for a adapter cable that will adapt a cisco blue console cable to a 11000 series CSS (but NOT a ArrowPoint branded CSS, I don’t think). I used phone tap splices to make mine, but you could also probably figure out how to correctly stick the li’l colored wires into a RJ-45 on each end to get this result. Then I used a RJ45 female-female to connect mine to a Cisco Blue console cable).

11500 CSSes use the standard cisco blue cable.

(p.s. Thanks to Kayti for correcting the most obvious of my spelling and grammar errors, and also holding a voltmeter probe on one of the RJ45 ends while I was reverse-engineering my handmade cable to write this note)

(p.p.s. Thanks to Allie for tangling his claws in the cable while I was trying to reverse engineer it by myself, reminding me that reverse engineering is best done as a social activity.. especially when you are reverse engineering your own work)

Just a reminder for you linux admins – chmod is not the end of file permissions in ext2/ext3. You also need to lsattr/chattr to cover all your file permission bases. Thanks to DoctorWho for the tip.