RJ connectors

Definition of RJ connectors in The Network Encyclopedia.

RJ connectors

A family of push-and-click connectors for twisted-pair wiring in telephone and network wiring. RJ stands for Registered Jack. RJ types define both a jack or receptacle (female) and a plug (male) type of connector. The most common types of RJ connectors are as follows:
  • RJ-11 connector:
    A 4-wire or 6-wire telephone-type connector that connects telephones to wall plates. RJ-11 supports up to six wires, but usually only four are used with the two-pair twisted-pair cabling commonly found in telephone cabling.

     

  • RJ-45 connector:
    An 8-wire telephone-type connector used with twisted-pair cabling for connecting computers, wall plates, patch panels, and other networking components. RJ-45 is the standard type of connector for both unshielded twisted-pair (UTP) and shielded twisted-pair (STP) cabling in star-topology Ethernet networks such as 10BaseT and 100BaseT4. RJ-45 is defined in International Organization for Standardization (ISO) standard 8877.

     

  • RJ-48 connector:
    An 8-wire telephone-type connector used with twisted-pair cabling for connecting T1 and 56-KB digital data service (DDS) lines. RJ-48 uses the same jack as RJ-45 but uses a different pinning, with one pair of wires to transmit signals, one pair to receive signals, one pair for drain, and one unused pair (reserved for future use). RJ-48 connectors come in three varieties: RJ-48C and RJ-48X for connecting T1 lines, and RJ-48S for connecting 56-KB DDS lines.

     

NOTE

The diagram shows RJ-11 and RJ-45/48 connectors, which are used to terminate both ends of UTP cabling. Pins are labeled 1 through 4 or 1 through 6 for 4-wire and 6-wire RJ-11, and 1 through 8 for 8-wire (four-pair) RJ-45/48. Cables can be straight-pinned or cross-pinned, depending on their use. For example, a straight-pinned RJ-45-terminated UTP cable is used to connect a computer to a 10BaseT hub, while a cross-pinned cable or crossover cable is used to connect two computers directly or to connect two hubs.

 RJ connectors
Graphic R-8. RJ connectors.

The following table shows the pinning for these various cables, with the colored wires coded as follows:

  • Y = yellow
  • G = green
  • R = red
  • W = white
  • S = silver
  • OR = orange
  • BL = blue
  • BK = black
  • BN = brown

If these colors are combined in striped cables, the coloring is coded OR/W for orange/white or orange with white striping, and so on. RJ-11 and RJ-45 cables generally use solid-color wires, while RJ-48 cables are usually striped. Note that RJ-45 has two types of cross-pinning: 568A/B and USOC. If the pinning of a wire is listed as Y (14), it means that the yellow wire is connected to pin 1 at one end and to pin 4 at the other.

Types of Cable Pinning

Connector/Cable Pinning
RJ-11 straight (4-wire)
Y (1-1), G (2-2), R (3-3), BL (4-4)
RJ-11 crossed (4-wire)
Y (1-4), G (2-3), R (3-2), BL (4-1)
RJ-11 straight (6-wire)
BL (1-1), Y (2-2), G (3-3), R (4-4), BK (5-5), W (6-6)
RJ-11 crossed (6-wire)
BL (1-6), Y (2-5), G (3-4), R (4-3), BK (5-2), W (6-1)
RJ-45 straight (8-wire)
BL (1-1), OR (2-2), BK (3-3), R (4-4), G (5-5), Y (6-6), BN (7-7), S (8-8)
RJ-45 USOC crossed (8-wire)
BL (1-8), OR (2-7), BK (3-6), R (4-5), G (5-4), Y (6-3), BN (7-2), S (8-1)
RJ-45 568A/B crossed (8-wire)
BL (1-3), OR (2-6), BK (3-1), R (4-5), G (5-4), Y (6-2), BN (7-8), S (8-7)
RJ-48C straight (8-wire)
OR/W (1-1), W/OR (2-2), (3-3) unused, BL/W (4-4), W/BL (5-5), (6-6) unused, BL drain (7-7), OR drain (8-8)
RJ-48C crossed (8-wire)
OR/W (1-4), W/OR (2-5), (3-3) unused, BL/W (4-1), W/BL (5-2), (6-6) unused, BL drain (7-7), OR drain (8-8)


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