Connectors and Transceivers

Cabling guides often skimp on the connector info, and actually, connectors are one of the most frustrating areas for LAN designers.  When ordering, you need to know the specs, the shape, whether it's a twist or snap-in, male or female, are terminators required, etc, etc, etc.  

10BASE-T (twisted pair)

The most common TP cable is the 8-strand UTP RJ-45 connector :

       

 


RJ45 Wall Cavity (Receptacle)
T568B is rarely used !!

TP Color Schemes

There are two wiring sequences, where the wires and color codes are matched to the RJ-45 pins :

The colors schemes are listed below with traditional nomenclature of Base/Stripe, where the Base coat color is listed first, followed by the Stripe color.  For example, White/Blue means the insulated sheath base color is white (not paint - the actual material is white), with stripes or dashes of the secondary color, Blue, painted on.

Here are the Preferred color pairs - they are not shown in any particular order:

Here are the Preferred color scheme pinouts. Pair 4-5 has always been used for voice, so the Ethernet standards left that pair alone - however, most buildings use separate cables for data and voice !!  Therefore, for Ethernet, 4-5 and 7-8 are not normally used.    The Ethernet transmit/receive pairs are shown as 1-2, and 3-6.  


T568A Color Codes for DTE (DCE is reversed, see below)
T568B is rarely used !!

NOTE:  quite often, the standard for the coloring of the wire insulation is not exactly followed, but it is still easy to tell which is which.  In many cases the secondary wire will be solid colored - for example, Pin2 wire would be solid green, Pin 4 solid blue, etc.  Also, the primary wire is often striped with one long horizontal white stripe.

DTE (Data Terminal Equipment) vs DCE (Data Communications Equipment) -the only reason that these two types of equipment are distinguished, is so that manufacturers and users alike will know which pins transmit and which receive, as shown below:

 

10Base5 (ThickNet - "Frozen Garden Hose") Connections

Cable Type: Heavy duty co-axial (50W), approximately 9.5mm or 10.3mm diameter
Maximum segment length: 500m
Maximum nodes per segment: 100
Terminators must be placed at both ends of the segment

The ancient 10Base5 cable was coined as "Frozen Garden Hose" due to the large, barely flexible coax cable.  The direct connection to the end station is a DB-15 socket is called AUI (Attachment Unit Interface).  It's very name implies it requires an "attachment unit" to be connected to it  .  .  .  i.e., a converter called a Transceiver.  The transceiver can be directly connected to the DB-15 socket, or an AUI cable can be used.  The AUI cable length, due to poor cross-talk, should be at least 2.5 M but not more than 50 M.

        

Transceivers

The Transceiver is near the computer end of the station drops.  It converts the DB-15 AUI to either Twisted pair RJ-45,  2-wire Coax (center conductor and shielding), or even fiber optic cable.

A ThickNet Ethernet segment consists of a long coax cable that snakes through building, and Ethernet Taps are attached to the cable at 2.5m intervals - these are the only points at which taps may be attached !! An electronic module, the MAU (Medium Attachment Unit) is connected to the taps and has a DB-15 interface.

The stations are connected to the MAU taps via special AUI cable. The AUI cable (DB-15 on both ends) can be up to 50m long - therefore the 2.5 M restriction on where taps can be located is not really a problem. The AUI cable is a 15 core cable fitted with 'D' connectors.
 

10Base2 (ThinNet) Connections

Cable Type: Co-axial, RG58 (50W), approx. 4.8mm dia.
Maximum segment length: 185m
Maximum nodes per segment: 30
Terminators must be placed at both ends of the segment

A ThinNet Ethernet segment consists of a long coax cable that snakes through building (usually above the ceiling tiles), and drops are inserted for each of the stations.  The most common drop interface is the "T" connector, which inserts the station into the ThinNet bus while preserving the continuity of the bus.

*** ThinNet can also use a transceiver, but only in rare cases where the station has only an AUI port.  Most stations have Thinnet NIC's with BNC connectors.

 

**** Optical Connectors

see also  http://www.seikofiber.com/  or  http://www.fibersource.net/products/connectors/connectors.htm 

SC - “Subscription Channel” connector. A push-pull type of optical connector that originated in Japan. Features high packing density, low loss, low back reflection, and low cost. High-precision ceramic ferrule. Snap-in locking mechanism for positive
latching. Keyed body for repeatability and intermateability. Ideal for high-density applications.

FC - A threaded optical connector that originated in Japan. Good for single-mode or multimode fiber and applications requiring low back reflection. All-zirconia ceramic ferrule for durability, High-performance threading mounting system. Keyed body for repeatability and intermateability. Primarily used with singlemode fibers. Used in telephone, instruments and high-speed communication links.

ST – “Straight Tip” connector that connects with a half-turn twist. Popular fiber optic connector originally developed by AT&T. Precise zirconia ceramic ferrule. Easy-to-assemble, one-piece bayonet mounting system. For both singlemode and multimode fibers using in communication applications.

D4 - Composite zirconia ceramic ferrule for durability. High-performance threading mounting system. Keyed body for repeatability and intermateability.

LC - Precision PC polished Zirconia cermic ferrule. RJ45 push-pull style housing and latching. Half the size of standard connectors. For private and public networks.

MU - 1.25mm diameter ferrule for compact multiple optical connectors and self-retentive mechanism for backplane applications. For high-speed data communications, voice networks, telecommunications and high-density DWDM applications.

LC