HELP: External 250G USB screwed with GParted
Rick Stevens
rstevens at internap.com
Mon Jan 21 18:53:09 UTC 2008
On Mon, 2008-01-21 at 12:16 -0600, Mikkel L. Ellertson wrote:
> Mikkel L. Ellertson wrote:
> > I could have sworn that the CAT 3 cable I used for networking was 4
> > pair, and not 2 pair. I can remember some 2 pair cable use for POT
> > connections, but every networking application was 4 pair. Now, both
> > 10BaseT and 100BaseTx only use 2 pair, but the cable is normally 4 pair.
> > Now, there is a difference a physical difference between CAT 3 and CAT
> > 5, but it has more to do with how the pairs are twisted together then
> > the number of wires. The number of wists/inch, and the relationship
> > between the number of twists in each pair change the electrical
> > characteristics of the cable. (Each pair has a different twist rate.) I
> > think how the pairs are twisted together in the cable is also specified.
> >
> Not enough coffee - Both CAT 3 and CAT 5 cable are available in
> different number of pairs, but 4 pair tends to be the most common in
> CAT 5 and CAT5e. You want to have fun, try terminating a 100 pair
> CAT 3 cable. At least with CAT 5, they tend to bundle each set of 5
> pair in their own jacket inside the main cable. (I would rather have
> them bundled in 4 pair groups - I hate wasting 5 pair of a 25 pair
> cable when doing networking. I would rather have 5 groups of 4 pair
> for a 20 pair cable.)
Most CAT5e 25-pair I've seen don't bundle five pairs in a separate
jacket...it's just a standard 25-pair telco cable that meets 5e specs
(and I've even seen CAT6 versions of the same cable).
I've used the 5e stuff a BUNCH of times...typically to cross-connect
racks using 24-port patch panels. Each panel requires four 25-pair
cables and you sacrifice a single pair per 25-pair cable. I've pushed
gigabit across it with no problems--I've even pushed 10GB across it with
a bit less success (haven't tried the CAT6 version, but I don't design
data centers much anymore).
>
> Mikkel
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- Rick Stevens, Principal Engineer rstevens at internap.com -
- CDN Systems, Internap, Inc. http://www.internap.com -
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- Never test for an error condition you don't know how to handle. -
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