Catalyst 2950 Switch Hardware Installation Guide, August 2004
Connectors and Cables
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Connectors and Cables

Table Of Contents

Connectors and Cables

Connector Specifications

10/100 Ports

10/100/1000 Ports

Connecting to 10BASE-T and 100BASE-TX Devices

Connecting to 1000BASE-T Devices

LRE Port

100BASE-FX and 1000BASE-SX Ports

1000BASE-X GBIC Module Ports

1000BASE-T GBIC Module Ports

GigaStack GBIC Module Ports

SFP Module Ports

Console Port

Identifying a Crossover Cable

Cable and Adapter Specifications

Two Twisted-Pair Cable Pinouts

Four Twisted-Pair Cable Pinouts for 10/100 Ports

Four Twisted-Pair Cable Pinouts for 1000BASE-T Ports

RJ-21 Cable Pinouts

Adapter Pinouts


Connectors and Cables


This appendix describes the connectors, cables, and adapters that you use to connect the switch to other devices.

Connector Specifications

These sections describe the connectors used with the Catalyst 2950 switches and contains this information:

10/100 Ports

10/100/1000 Ports

100BASE-FX and 1000BASE-SX Ports

LRE Port

GigaStack GBIC Module Ports

SFP Module Ports

Console Port

10/100 Ports

The 10/100 Ethernet ports use standard RJ-45 connectors and Ethernet pinouts with internal crossovers, as shown by an X in the port name. These ports have the transmit (TD) and receive (RD) signals internally crossed so that a twisted-pair straight-through cable and adapter can be attached to the port. Figure B-1 shows the pinout.

When connecting 10/100 ports to other devices, such as servers, workstations, and routers, you can use a two or four twisted-pair, straight-through cable wired for 10BASE-T and 100BASE-TX. Figure B-10 shows the two twisted-pair, straight-through cable schematics. Figure B-12 shows the four twisted-pair, straight-through cable schematics.

When connecting the ports to other devices, such as switches or repeaters, you can use a two or four twisted-pair, crossover cable. Figure B-11 shows the two twisted-pair, crossover cable schematics. Figure B-13 shows the four twisted-pair, crossover cable schematics.

You can use Category 3, 4, or 5 cabling when connecting to 10BASE-T devices. You must use Category 5 cabling when connecting to 100BASE-TX devices.


Note Use a straight-through cable to connect two ports only when one port is designated with an X. Use a crossover cable to connect two ports when both ports are designated with an X or when both ports do not have an X.


Figure B-1 10/100 RJ-45 Pinouts

10/100/1000 Ports

The 10/100/1000 Ethernet ports on Catalyst 2950T-24, Catalyst 2950T-48-SI, and Catalyst 2950 Long-Reach Ethernet (LRE) switches use standard RJ-45 connectors. Figure B-2 shows the pinout.


Note On the Catalyst 2950 LRE switches, the four input uplink ports are bundled as two logical ports, each consisting of a copper 10/100/1000 port and a fiber-optic small form-factor pluggable (SFP) module slot, respectively.

Within each logical port, you can use only the copper or the fiber-optic port at one time. If the Catalyst 2950 LRE switch senses more than two connections for both logical ports, the switch chooses the fiber-optic connections over the copper connections in default operation.

See the "SFP Module Slots" section for more information on LRE uplink logical ports.


Connecting to 10BASE-T and 100BASE-TX Devices

When connecting the ports to 10BASE-T and 100BASE-TX devices, such as servers, workstations, and routers, you can use a two or four twisted-pair, straight-through cable wired for 10BASE-T and100BASE-TX. Figure B-10 shows the two twisted-pair, straight-through cable schematics. Figure B-12 shows the four twisted-pair, straight-through cable schematics.

When connecting the ports to 10BASE-T- and 100BASE-TX devices, such as switches or repeaters, you can use a two or four twisted-pair, crossover cable. Figure B-11 shows the two twisted-pair, crossover cable schematics. Figure B-13 shows the four twisted-pair, crossover cable schematics.

You can use Category 3, 4, or 5 cabling when connecting to 10BASE-T devices. You must use Category 5 cabling when connecting to 100BASE-TX devices.

Connecting to 1000BASE-T Devices

When connecting the ports to 1000BASE-T devices, such as servers, workstations, and routers, you must use a four twisted-pair, Category 5, straight-through cable wired for 10BASE-T, 100BASE-TX, and 1000BASE-T. Figure B-14 shows the straight-through cable schematics.

When connecting the ports to other devices, such as switches or repeaters, you must use a four twisted-pair, Category 5, crossover cable. Figure B-15 shows the crossover cable schematics.


Note Be sure to use a four twisted-pair, Category 5 cable when connecting to a 1000BASE-T device.



Note Use a straight-through cable to connect two ports only when one port is designated with an X. Use a crossover cable to connect two ports when both ports are designated with an X or when both ports do not have an X.


Figure B-2 RJ-45 Pinouts for 10/100/1000 and 1000BASE-T GBIC Module Ports

LRE Port

The LRE port uses a single 50-pin RJ-21 connector, as shown in Figure B-3. Each LRE port uses two pins. Because the Catalyst 2950ST-24 LRE and Catalyst 2950ST-24 LRE 997 switches use 48 pins, pin 25 on the top row and pin 50 on the bottom row are not used

The Catalyst 2950ST-8 LRE switch uses 16 pins. Pins 9 through 25 on the top row and pins 34 through 50 on the bottom row are not used.

Figure B-3 RJ-21 Connector

100BASE-FX and 1000BASE-SX Ports

The 100BASE-FX and 1000BASE-SX ports use MT-RJ connectors, shown in Figure B-4. These ports use 50/125- or 62.5/125-micron multimode fiber-optic cabling.

You can connect a 100BASE-FX or 1000BASE-SX port to an SC or ST port on a target device by using one of the MT-RJ fiber-optic patch cables listed in Table 2-1. Use the Cisco part numbers in Table 2-1 to order the patch cables that you need.

Figure B-4 MT-RJ Connector

1000BASE-X GBIC Module Ports

1000BASE-X Gigabit Interface Converter (GBIC) module ports use duplex SC connectors, as shown in Figure B-5.

Figure B-5 1000BASE-X SC Connector

1000BASE-T GBIC Module Ports

The 1000BASE-T GBIC module port uses one RJ-45 connector, as shown in Figure B-2.

GigaStack GBIC Module Ports

The GigaStack GBIC module ports use proprietary connectors, as shown in Figure B-6. The GigaStack GBIC cables are proprietary, high-data-rate cables with enhanced signal integrity and EMI protection.


Caution Do not use standard IEEE 1394 cables with the GigaStack GBIC.

Figure B-6 GigaStack Connector

SFP Module Ports

The Catalyst 2950 LRE switch uses SFP modules for fiber-optic and copper uplink ports. See the Catalyst 2950 LRE switch release notes for a list of supported SFP modules. See Figure B-7 and Figure B-8.

Figure B-7 Fiber-Optic SFP Module LC Connector


Warning Invisible laser radiation may be emitted from disconnected fibers or connectors. Do not stare into beams or view directly with optical instruments. Statement 1051


Figure B-8 1000BASE-T SFP Module RJ-45 Connector

Console Port

The console port uses an 8-pin RJ-45 connector. You can connect a switch to a PC through the console port and the supplied RJ-45-to-DB-9 adapter cable. If you want to connect a switch to a terminal, you need to provide an RJ-45-to-DB-25 female DTE adapter. You can order a kit (part number ACS-DSBUASYN=) with that adapter from Cisco. For console-port and adapter-pinout information, see Table B-3 and Table B-4.

Identifying a Crossover Cable

You can identify a crossover cable by comparing the two modular cable ends. Hold the cable ends side-by-side, with the tab at the back. The wire connected to the pin on the outside of the left plug should be the same color as the wire connected to the pin on the outside of the right plug. (See Figure B-9.)

Figure B-9 Identifying a Crossover Cable

Cable and Adapter Specifications

These sections describe the cables and adapters used with Catalyst 2950 switches.

Two Twisted-Pair Cable Pinouts

Four Twisted-Pair Cable Pinouts for 10/100 Ports

Four Twisted-Pair Cable Pinouts for 1000BASE-T Ports

RJ-21 Cable Pinouts

Two Twisted-Pair Cable Pinouts

Figure B-10 and Figure B-11 show the schematics of two twisted-pair cables for 10/100 ports.

Figure B-10 Two Twisted-Pair Straight-Through Cable Schematic for 10/100 Ports

Figure B-11 Two Twisted-Pair Crossover Cable Schematic for 10/100 Ports

Four Twisted-Pair Cable Pinouts for 10/100 Ports

Figure B-12 and Figure B-13 show the schematics of four twisted-pair cables for 10/100 ports.

Figure B-12 Four Twisted-Pair Straight-Through Cable Schematic for 10/100 Ports

Figure B-13 Four Twisted-Pair Crossover Cable Schematic for 10/100 Ports

Four Twisted-Pair Cable Pinouts for 1000BASE-T Ports

Figure B-14 and Figure B-15 show the schematics of four twisted-pair cables for 10/100/1000 ports on Catalyst 2950T-24 switches, Catalyst 2950 LRE switches, and 1000BASE-T GBIC module ports.

Figure B-14 Four Twisted-Pair Straight-Through Cable Schematic for 10/100/1000 and 1000BASE-T GBIC Module Ports

Figure B-15 Four Twisted-Pair Crossover Cable Schematics for 10/100/1000 and 1000BASE-T GBIC Module Ports

RJ-21 Cable Pinouts

Table B-1 lists the RJ-21 cable pinouts on the Catalyst 2950ST-24 LRE and Catalyst 2950ST-24 LRE 997 switches.

Table B-1 Catalyst 2950ST-24 LRE and Catalyst 2950ST-24 LRE 997 Switch RJ-21 Cable Pinouts 

Function
Pin
Pin
Function

Port 1 Tip

1

26

Port 1 Ring

Port 2 Tip

2

27

Port 2 Ring

Port 3 Tip

3

28

Port 3 Ring

Port 4 Tip

4

29

Port 4 Ring

Port 5 Tip

5

30

Port 5 Ring

Port 6 Tip

6

31

Port 6 Ring

Port 7 Tip

7

32

Port 7 Ring

Port 8 Tip

8

33

Port 8 Ring

Port 9 Tip

9

34

Port 9 Ring

Port 10 Tip

10

35

Port 10 Ring

Port 11 Tip

11

36

Port 11 Ring

Port 12 Tip

12

37

Port 12 Ring

Port 13 Tip

13

38

Port 13 Ring

Port 14 Tip

14

39

Port 14 Ring

Port 15 Tip

15

40

Port 15 Ring

Port 16 Tip

16

41

Port 16 Ring

Port 17 Tip

17

42

Port 17 Ring

Port 18 Tip

18

43

Port 18 Ring

Port 19 Tip

19

44

Port 19 Ring

Port 20 Tip

20

45

Port 20 Ring

Port 21 Tip

21

46

Port 21 Ring

Port 22 Tip

22

47

Port 22 Ring

Port 23 Tip

23

48

Port 23 Ring

Port 24 Tip

24

49

Port 24 Ring

No connect

25

50

No connect


Table B-2 lists the RJ-21 cable pinouts on the Catalyst 2950ST-8 LRE switches.

Table B-2 Catalyst 2950ST-8 LRE Switch RJ-21 Cable Pinouts 

Function
Pin
Pin
Function

Port 1 Tip

1

26

Port 1 Ring

Port 2 Tip

2

27

Port 2 Ring

Port 3 Tip

3

28

Port 3 Ring

Port 4 Tip

4

29

Port 4 Ring

Port 5 Tip

5

30

Port 5 Ring

Port 6 Tip

6

31

Port 6 Ring

Port 7 Tip

7

32

Port 7 Ring

Port 8 Tip

8

33

Port 8 Ring

No connect

9

34

No connect

No connect

10

35

No connect

No connect

11

36

No connect

No connect

12

37

No connect

No connect

13

38

No connect

No connect

14

39

No connect

No connect

15

40

No connect

No connect

16

41

No connect

No connect

17

42

No connect

No connect

18

43

No connect

No connect

19

44

No connect

No connect

20

45

No connect

No connect

21

46

No connect

No connect

22

47

No connect

No connect

23

48

No connect

No connect

24

49

No connect

No connect

25

50

No connect


Adapter Pinouts

Table B-3 lists the pinouts for the console port, the RJ-45-to-DB-9 adapter cable, and the console device.

Table B-3 Console Port Signaling and RJ-45-to-DB-9 Adapter Cabling  

Console
Port (DTE)
RJ-45-to-DB-9
Adapter Cable
Console
Device
Signal
RJ-45 Pin
DB-9 Pin
Signal

RTS

1

8

CTS

Not connected

2

6

DSR

TxD

3

2

RxD

GND

4

5

GND

GND

5

5

GND

RxD

6

3

TxD

Not connected

7

4

DTR

CTS

8

7

RTS


Table B-4 lists the pinouts for the console port, RJ-45-to-DB-25 female DTE adapter, and the console device.


Note The RJ-45-to-DB-25 female DTE adapter is not supplied with the switch. You can order a kit (part number ACS-DSBUASYN=) with that adapter from Cisco.


Table B-4 Console Port Signaling and Cabling Using a DB-25 Adapter 

Console
Port (DTE)
RJ-45-to-DB-9
Adapter Cable
RJ-45-to-DB-25
Terminal Adapter
Console
Device
Signal
RJ-45 Pin
DB-9 Pin
DB-25 Pin
Signal

RTS

1

8

5

CTS

Not connected

2

6

6

DSR

TxD

3

2

3

RxD

GND

4

5

7

GND

GND

5

5

7

GND

RxD

6

3

2

TxD

Not connected

7

4

20

DTR

CTS

8

7

4

RTS