Black Box ServSwitch Duo KV6EXT-R2, Руководство пользователя

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SERVSWITCH ™ DUO EXTENDER
Appendix A:
Guidelines for Twisted-Pair Cabling
To connect your ServSwitch™ Duo Extender to a ServSwitch Duo, you can use
either shielded twisted-pair (STP) or unshielded twisted-pair (UTP) cable. It should
be pinned straight-through and paired according to the TIA-568A or (preferred)
-568B specification, as shown in Figure A-1 on the next page. Category 5 cable will
give the best results for distances up to 200 m (655 ft.), but you should be able to
use Category 3, 4, or 5e if you keep the distance short (not more than 100 m
[325 ft.]).
Avoid using cabling rated as “Level 6,” “Level 7,” etc., for data rates above
155 Mbps; the large differences between the twist ratios of the wire pairs in these
cables cause the video signals from the Duo’s CPUs to get out of sync with each
other.
CAUTION!
Do not use cables paired according to the USOC specification—Pin 1
with 2, 3 with 4, 5 with 6, and 7 with 8. These will work badly and will
yield a horrible picture.
We recommend a solid-core CAT5 cable such as product codes EYN737MS
(preterminated) or EYN840A (unterminated bulk); specify the length you’d like when
you order. Terminate any unterminated cable with high-quality shielded RJ-45
plugs such as those in our FM732 (unshielded) and FM733 (shielded) 25-packs.
CAUTION!
Keep in mind that if you use shielded twisted-pair cable, the maximum
distance at which the Extender will operate will be cut at least in half, to
no farther than 100 m (325 ft.).
All twisted-pair cables are built in such a way that each of the twisted pairs has a
slightly different twist ratio. This is done to reduce the electrical crosstalk between
signals carried on adjacent pairs. Because of this, the wire distance that an
electrical signal has to travel is different for the different pairs. This does not
normally cause a noticeable problem—in fact, the twist differences have no effect
at all on digital signals such as network data. But if you’re sending higher video
resolutions (which are analog signals) across long cables, you might start to see
color separation caused by the red, blue, and green signals arriving at the Extender
at slightly different times.
If this happens, you might be able to improve your video by reterminating your
cable so that the video signals are on the pairs whose twist ratios are the closest to
each other. Most network-quality cables have one pair that’s much more tightly