Thu, 12 Jun 2008
If fibre goes down in a forest, does the twisted pair hear it scream?
So at $work[0] we're trying to bring up a new service for a customer. It's a
2meg service from T, which terminates on our side like so:
fibre -> managed media converter -> twisted pair -> router
We think we're ready to turn it up and a T technician is booked. For 01:30am
due to customer requirements. Sigh.
Technician reports he can't see either the media converter nor the router. He's
on the "basement switch" (a designation which means nothing to yours truly,
especially at that hour of the morning). Eventually my sleep deprived haze
allows me to parse that he is on a switch in the facility and can't connect to
the service.
Except our understanding is that their end of the service doesn't terminate in
the facility. Their switch is in one meet-me-room but it had cable tray / riser
capacity issues. So this service's fibre went to the meet-me-room at the other
end of the building. Where T doesn't have a switch. But they did have some
spare fibre already pulled from an exchange. So a fibre tie later and our
service terminates elsewhere. And in my blubbering state I can't convince the
technician of this. Cutover canceled. Furrfu.
So what does the subject have to do with this saga I hear you ask?
The technician wanted me to pull the twisted pair from the router to check for
link protocol going down on an interface of the switch he was logged into to.
Even presuming he was on the right switch, my original reaction was that it
wouldn't work because the media converters act like bridges, not repeaters, and
the link protocol wouldn't change at his end.
I wanted to confirm / deny this ungodly hour of the morning theory, but my
Google-fu appears to be suffering 5 month old child process lossage. JohnF did the heavy lifting for me and
turned up this
question and answer
which covered a similar scenario. The pertinent
response that address my question is:
Coming in a bit late here, but... Has the OP looked at how the media converter is set up? Many media converters have a test mode where a down link status is not passed from one side to another. Once you take it out of test mode, it will pass status. Usually it's a small push button, or a switch. Sean
So the answer to my question is: it depends!
[2008/06/12 / tech / hardware permanent link]
Sun, 03 Feb 2008
CPU lines multiplying like rabbits?!?
So, I admit it's been a while since I really looked into x86 hardware, but I
remember a time when Intel and AMD (and any other CPU manufacturer...) had 2-3
lines at most. There was the one aimed at servers pitched at a speed/feature
set, the one aimed at desktops pitched at a price point and possibly a mobile
chip pitched at a low power/long battery life scenario.
Now you have 47 different types.
I think their thought process must go:
- Is it low power or high performance?
- How many cores does it have?
- Uniprocessor only or made for multiprocessor systems?
- 32bit or 64bit?
- Is it built down to a price or up to feature set?
And then throw in some variations in bus speeds and L2 cache sizes in the different models in the same line. To top it off give the models confusing names not based on any specification of the acutal CPU. Whimper.
Almost makes you want to be a luddite...
