Hi all,
anybody out there can explain the difference between FTP (Foiled Twisted
Pair) and STP (Shielded Twisted Pair) cables used for Ethernet links.
In Ethernet standard IEEE 802.3 (2000) I find only a definition of STP
(herebelow in copied and pasted from the standard - page 28):
In a vendor's catalog, I found a definition of FTP as
<<1.4.249 shielded twisted-pair (STP)cable: An electrically conducting
cable,comprising one or more ele-
ments,each of which is individually shielded.There may be an o erall
shield,in which case the cable is
referred to as shielded twisted-pair cable with an o erall shield (from
ISO/IEC 11801:1995).Speci .cally
for IEEE 802.3 100BASE-TX,150 . balanced inside cable with performance
characteristics speci .ed to
100 MHz (i.e.,performance to Class D link standards as per ISO/IEC
11801:1995).In addition to the
requirements speci .ed in ISO/IEC 11801:1995,IEEE 802.3 Clauses 23 and 25
provide additional perfor-
mance requirements for 100BASE-T operation o er STP.>>
The reason of my inquiry is that we bought samples of "STP" and "FTP" cat.5
cables for 10bT ethernet applications from different vendors and to our
surprise we discovered that both "STP" and "FTP" types have an overall
(external) shield made of aluminum foil, but no shields on individual wires
or wire couples (as per 802.3 definition above).
Any inputs, suggestions etc. would be appreciated.
Paolo
-------------------------------------------------------------------------------
Paolo Roncone
EMC Compliance Engineer - Cisco Photonics Italy
via Philips 12 - Monza (MI) 20052
mailto:pronc...@cisco.com
phone: +39 039209 1538
fax: +39 039209 2036
