Archive for the 'Tech' Category

Finding a dodgy cable with Cisco Catalyst cable diagnostics

Wednesday, September 14th, 2011

We had a couple of servers that were themselves reporting as connected @ 1G/FD and also the same for the switchports they were connectd to. Yet iperf between the two boxes was pretty pants – about 34MBits/sec.
So I had a think and looked up how to test the cable lengths, which also showed me that the twisted pairs that make up an ethernet cable weren’t all working properly.
After the cable change, iperf between the same two machines showed  941 Mbits/sec, which is a vast improvement!

before cable change

core02#show cable-diagnostics tdr interface gigabitEthernet 1/0/11
TDR test last run on: August 12 19:50:34
Interface Speed Local pair Pair length Remote pair Pair status
--------- ----- ---------- ------------------ ----------- --------------------
Gi1/0/11 1000M Pair A 7 +/- 10 meters Pair B Normal
Pair B 0 +/- 10 meters Pair A Open
Pair C 1 +/- 10 meters Pair D Open
Pair D 0 +/- 10 meters Pair C Open
core02#show cable-diagnostics tdr interface gigabitEthernet 1/0/12
TDR test last run on: August 12 19:50:50
Interface Speed Local pair Pair length Remote pair Pair status
--------- ----- ---------- ------------------ ----------- --------------------
Gi1/0/12 1000M Pair A 1 +/- 10 meters Pair A Open
Pair B 7 +/- 10 meters Pair B Normal
Pair C 0 +/- 10 meters Pair C Open
Pair D 0 +/- 10 meters Pair D Short/Crosstalk

after cable change

core02#show cable-diagnostics tdr interface gigabitEthernet 1/0/11
TDR test last run on: August 12 20:10:32
Interface Speed Local pair Pair length Remote pair Pair status
--------- ----- ---------- ------------------ ----------- --------------------
Gi1/0/11 1000M Pair A 345 +/- 10 meters Pair B Normal
Pair B 345 +/- 10 meters Pair A Normal
Pair C 345 +/- 10 meters Pair D Normal
Pair D 345 +/- 10 meters Pair C Normal
core02#test cable-diagnostics tdr interface gigabitEthernet 1/0/12
TDR test started on interface Gi1/0/12
A TDR test can take a few seconds to run on an interface
Use 'show cable-diagnostics tdr' to read the TDR results.
core02#show cable-diagnostics tdr interface gigabitEthernet 1/0/12
TDR test last run on: August 12 20:11:20
Interface Speed Local pair Pair length Remote pair Pair status
--------- ----- ---------- ------------------ ----------- --------------------
Gi1/0/12 1000M Pair A 347 +/- 10 meters Pair B Normal
Pair B 347 +/- 10 meters Pair A Normal
Pair C 347 +/- 10 meters Pair D Normal
Pair D 347 +/- 10 meters Pair C Normal

You are totally surrounded! (finally)

Wednesday, May 11th, 2011

After many years of struggling with trying to get my AppleTV (mk1) to a state where the surround sound actually works, I finally have it solved.
The answer was, buy a new surround decoder box.
So now I have a nice, shiny Yahama A/V amp that decodes AC3 and DTS from the optical output of the ATV. Yet not just this wonderful feature is what makes this new amp great. What it has also done is about halve the amount of cabling in my bedroom A/V setup. Whereas previously where was a separate hifi amp, surround decoder and speaker set, A/V switchbox, 2 optical/co-ax transceivers + power supplies – now there is the one gox to rule them all as it were. So now I have (almost) all the previous kit plugged into the same device and can switch between it, with the bonus of 7.1(!) surround capabilities.
So I can switch between the ATV, Wii, Galaxy Tab multimedia dock, Sega Saturn, Humax PVR & Toshiba DVD player from one place, each with their own appropriate speaker settings auto-selected.
The only thing it doesn’t do is transcode between HDMI/Component/Composite video (each source-type only talks to its corresponding output), so I’ll still have to select differing inputs on the projector, although the HDMi out from the amp will go through a HDFury box to convert it to component as that’s what my projector supports… Which means I still need the vga sswitchbox that currenty links the sources to the projector, but that’s not too much of a bind really.
So now all the 720p movies that previously played without sound (like the Star Trek movie collection and also the as yet unwatched-in-one-sitting Bourne trilogy) all play in HD (thanks to XBMC now having GPU accelleration on the ATV) and with full surround sound.
SO thank you Yamaha for enabling a geek to lie in bed and be appropriately surrounded by really-big-screen entertainment!
Just another reason for not having to leave the house! ;)

rooted galaxy tab turns itself off when power button pressed

Sunday, May 8th, 2011

This was driving me crazy!
Whenever I unplugged the device from usb and then pressed the power button to turn off the screen, the thing would turn itself off!

What I found was, me using SetCPU to clock the Tab down to 100MHz when screen off, was actually causing the problem.
so the solution was set the ‘screen off’ profile to a minimum of 200MHz with the ‘ondemand’ scaling setting and all is good… :)

http://forum.xda-developers.com/archive/index.php/t-879264.html

“Are you using setcpu? I had the same problem when trying to use conservitave or set the minimum to 100mhz. Currently I use ondemand with a minimum of 200mhz”

Galaxy Tab + dropbox + docs to go + keyboard = laptop replacement

Wednesday, May 4th, 2011

So recently I bought myself a Samsung Galaxy Tab as it’s “not an iPad”, holdable in one hand and runs the same version of Android as my HTC Desire Z.
Slightly more recently than that, I went a bit crazy and bought a number of the accessories, including the keyboard dock.
Today I discovered that the android version of dropbox does actually do two-way sync, instead of just allowing you to download files from your dropbox. Obvious when you think about it, but I hadn’t tried it before.
What I was trying to do was to find a portable way of editing my expenses spreadsheet and for this I turned to ‘Documents To Go’. Mostly I’ve tried to keep to the ‘free’ android software in the market, however with now having two devices linked to the same google account, it seemed like a reasonable option.
So now, I can download the file from my dropbox onto the Tab, edit in D2G and on saving it gets uploaded back to the dropbox.
So basically what this means is, that the tablet with the keyboard is now a pretty reasonable laptop replacement. If I want a bigger view, I can always plug into a TV with the video out cable. This could also make a very portable presentation systekm, with the powerpoint (spit spit) support of D2G.
Personally, what I would like to see is a combination of the desktop dock that has the HDMI output, with the keyboard, which would then put full-screen HD video, or at least the linkability of that, along with the typability (?) that the keyboard dock brings.
Therefore replacing a more bulky laptop with something you can take as a tablet when you need to move about (the office, primarily), then get back to your desk, slot in the tablet and write up your notes that could also be displayed on the bigger screeen connected via the HDMI port (maybe in the future!).

Grrr!!!

Sunday, May 7th, 2006

Was installing quicktime after reinstalling my Tosh laptop with XP so it could run with the BCD2000 (new drivers, runs well now ;) ) and it came up with an unpacking error, with a suggestion to reboot my computer. Though ok, best to try it again cleanly, then spent the next hour or so figuring out why it wouldn’t start up properly!

It would seem that somehow the display drivers had been corrupted, which is really strange considering they should be separate!

Now that’s fixed, here’s getting on with installing all the other a/v s/w and seeing if it’ll sync to midi clock from Traktor :) (via midi yoke virtual midi ports).
Then maybe the midi-over-lan drivers.

As part of the portable karaoke system…

Sunday, April 23rd, 2006

The Alesis Picoverb I bought off of Ebay a couple of weeks ago is now velcro’ed underneath my little Behringer UB502.
At the moment it’s connected via the tape out/in (using those connections like an fx send/return) which seems to work ok as long as the input on the Picoverb isn’t turned up too much otherwise it feeds back… I guess I could connect it in line with the master out and that would stop that problem.

Anyway, it’s a tiny little portable package and it fits really cool :)
Also, I had a phone call yesterday telling me that FINALLY after originally ordering from Turnkey LAST MAY (!), my spanking new (also) Behringer BCD2000 USB DJ controller (which I should be able to use with some of the VJ software I’ve got, thereby making it a multi-discipline usage thingy) is in stock and waiting for them to be told my new debit card number on Tuesday, hopefully for delivery Wednesday. Music Tech geek-toy heaven (hopefuly!). :)