GSTERNER.NOV

GUIDE TO TOKEN-RING CABLING
By Gregg Sterner
The author is a consultant for Harris Adacom Corp. in Dallas.
Until the advent of networking, the cabling in a customer's
environment was an easy task since each device required its own
dedicated cable.  However, network cabling systems are designed
to handle many devices simultaneously and at higher clock speeds. 
Because of these requirements, network cable systems are more
critical and complicated than the conventional systems.
The following guide is a general overview of the cable types that
are found in Token-Ring and Ethernet networks.  These cables meet
the ANSI/IEEE 802 and IBM standards.  Any other cable types are
unacceptable.  If you have any questions concerning network
cabling systems, please contact Harris Corporation's NetComm
Services department of the Customer Support Division.
The following illustrations are reprinted courtesy of Anixter
Wiring Systems, Anixter Bros., Inc.  The AC part number that
appears with the IBM part number is the Anixter part number.
Token-Ring Networks
IBM Type 1 and 2 cable will have the IBM specification part
number printed on the side of the cable.  The data conductors in
this cable have a thicker insulation than most other data
cabling.
Type 1 Data Cables:
o IBM (See Figure 1.)
o Plenum and Non-Plenum
o Two twisted pairs of No. 22 AWG solid conductors for data
communication are enclosed in a tinned copper braid shield
covered with an appropriate sheath.
o IBM Part No. 4716748 Non-Plenum
o IBM Part No. 4716749 Plenum
o IBM Part No. 4716734 Outdoor/Aerial
Type 2 Data and Telephone Cables:
o IBM (See Figure 2.)
o Plenum and Non-Plenum
o Two twisted pairs of No. 22 AWG solid conductors for data
communication are enclosed in a tinned copper braid shield.  Four
additional pairs of No. 22 AWG solid conductors for telephones or
other data used are also included inside the cable jacket.
o IBM Part No. 4716739 Non-Plenum
o IBM Part No. 4716738 Plenum
The four pair of telephone grade wires in the Type 2 cable are
No. 22 AWG and do not fit into a standard RJ11 modular telephone
plug.
A Telephone Jack Connector (IBM Part No. 8310575 or 6091030),
RJ11 or RJ45 jack (shown in Figure 3) must be used to terminate
these wires at the user end of the cable.  A No. 24 AWG jumper
cable with a RJ11 or RJ45 modular plug for the voice equipment or
modem is then plugged into the jack.  The voice grade wires at
the other end of the Type 2 cable are then connected to a Telco
66 type punch-down block for connection into the telephone
system.
When using the TokenView 4 Network Manager System from Proteon
Corporation, a Type 2 cable should be used for the backbone cable
and the TokenView PC node cable.  This allows two pair of the
voice grade pair wires to be used for the serial bus interface
between the TokenView PCs and the Proteon MSAUs.
WARNING:  Never use any shielded twisted pair cable with a
stranded center conductor for the backbone or node cable. 
Stranded conductor cable should be used for patch cables and
short lobe cables, as Type 6 cable is electrically equivalent to
two-thirds the length of Type 1 cable.
Type 3 cable is basically telephone cable, and in most cases, the
ID number is not printed on it.  Typically, only telephone cable
that was installed within the last three years is really the
current Type 3 cable.
Many customers presume that since telephone cable is twisted pair
cable, then any type of twisted pair cable can be used.  This is
not the case.
If a cable has a part number such as a Beldon number, an AWM
Style number or similar designation, it is not an acceptable
cable.  Contact NetComm Services for assistance in identifying
this cable, or send a sample of it in to NetComm Services in
Dallas for identification.
If Type 3 cable is to be used, then a Type 3 Media Jumper (shown
in Figure 4) and a Type 3 Media filter (shown in Figure 5) must
be used.
Type 3 Media Jumper (IBM Part No. 6466944):
o IBM (See Figure 4.)
o This jumper carries the signal from the Type 66 connecting
block to a receptacle on a Multistation Access Unit or to a
distribution panel.  The cable is four meters (13 feet) long and
has an IBM Cabling System data connector on one end.  On the
other end are four individual, color-coded wires that can be
inserted into a Type 66 connecting block.  
Type 3 Media Filter (IBM Part No. 6466941):
o IBM (See Figure 5.)
o The Type 3 Media Filter consists of a filter assembly housed in
a plastic enclosure, a nine-pin D-connector and an 8-foot cable
terminated with a six-pin (RJ11) modular plug.  The Type 3 Media
Filter limits the amount of radiated electrical energy to comply
with FCC regulations.
Type 1 Data Grade Media Filter (IBM Part No. 6466943):
o This filter is required in networks that use a combination of
Type 1 and Type 3 lobe cables.  This filter is used on the Type 1
lobe cables, while the Type 3 filter is used on the unshielded
twisted pair (Type 3) telephone cable.  These filters match the
different impedances of the Type 1 and Type 3 cables to prevent
excessive loading of the network.  CAUTION:  The node count for
this type of network cable system is limited to 72 nodes as
specified for Type 3 cable.
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