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Re: HELP: External 250G USB screwed with GParted



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 internap com -
- CDN Systems, Internap, Inc.                http://www.internap.com -
-                                                                    -
-   Never test for an error condition you don't know how to handle.  -
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