Contents

Appendix E  Cables· 1

Ethernet twisted pair cable· 1

RJ-45 connector 1

Cable pinouts· 1

Cable type· 2

Pin assignments· 3

Making an Ethernet twisted pair cable· 5

E1 cable· 5

Optical fiber 8

Optical fiber 8

Optical fiber cable· 9

Patch cord· 9

Pigtail cord· 9

Fiber connector 9

Precautions· 10

 

Appendix E  Cables

This chapter describes the cables used for connecting network ports.

Table 1 Cable description

Cable	Port type	Application	Reference
Console cable	Console port at one end and 9-pin serial port at the other end	Connects the console port of a router to a configuration terminal.	See "Setting up the configuration environment."
USB console cable	USB console port at one end and USB port at the other end	Connects the USB console port of a router to a configuration terminal.
Ethernet twisted pair cable	RJ-45 Ethernet interfaces	Connects RJ-45 Ethernet interfaces to transmit data.	Ethernet twisted pair cable
E1 cable	E1-HM96 Ethernet copper ports	Connects E1-HM96 Ethernet copper ports to transmit data.	E1 cable
Optical fiber	XFP/SFP+/SFP/CFP interfaces	Connects the optical interfaces to transmit data.	Optical fiber

 

Ethernet twisted pair cable

An Ethernet twisted pair cable consists of four pairs of insulated wires twisted together. It mainly transmits analog signals and is advantageous in transmitting data over shorter distances. The maximum transmission distance is 100 m (328.08 ft).

To extend the maximum transmission distance, you can use a repeater to connect two Ethernet twisted pair cables. You can use up to four repeaters to extend the maximum transmission distance to 500 m (1640.42 ft).

RJ-45 connector

An Ethernet twisted pair cable connects network devices through the RJ-45 connectors at the two ends. Figure 1 shows the pinouts of an RJ-45 connector.

Figure 1 RJ-45 connector pinout diagram

 

Cable pinouts

EIA/TIA cabling specifications define two standards: 568A and 568B for cable pinouts.

·     Standard 568A: pin 1: white/green stripe, pin 2: green solid, pin 3: white/orange stripe, pin 4: blue solid, pin 5: white/blue stripe, pin 6: orange solid, pin 7: white/brown stripe, pin 8: brown solid.

·     Standard 568B: pin 1: white/orange stripe, pin 2: orange solid, pin 3: white/green stripe, pin 4: blue solid, pin 5: white/blue stripe, pin 6: green solid, pin 7: white/brown stripe, pin 8: brown solid.

Cable type

Based on performance

Ethernet cables can be classified into category 3, category 4, category 5, category 5e, category 6, and category 7 cable based on performance. In LANs, category 5, category 5e, and category 6 are commonly used.

Table 2 Ethernet cable description

Type	Description
Category 5	Transmits data at a maximum speed of 100 Mbps, with a bandwidth of 100 MHz.
Category 5e	Transmits data at a maximum speed of 1000 Mbps, with a bandwidth of 100 MHz.
Category 6	Transmits data at a maximum speed of 10 Gbps, with a bandwidth of 250 MHz.

 

	NOTE: The RJ-45 Ethernet interfaces use category 5 or higher Ethernet twisted pair cables for connection.

 

Based on pinouts

Ethernet twisted pair cables can be classified into straight through and crossover cables based on their pinouts.

·     Straight-through: The pinouts at both ends comply with standard 568B, as shown in Figure 2.

·     Crossover: The pinouts at one end comply with standard 568B, and those at the other end comply with standard 568A, as shown in Figure 3.

Figure 2 Straight-through cable

 

Figure 3 Crossover cable

 

Pin assignments

Select an Ethernet twisted pair cable according to the RJ-45 Ethernet interface type on your device. An RJ-45 Ethernet interface can be MDI (for routers and PCs) or MDIX (for routers). For the pinouts of RJ-45 Ethernet interfaces, see Table 3 and Table 4.

Table 3 RJ-45 MDI interface pinouts

Pin	10BASE-T/100BASE-TX		1000BASE-T
	Signal	Function	Signal	Function
1	Tx+	Send data	BIDA+	Bi-directional data cable A+
2	Tx-	Send data	BIDA-	Bi-directional data cable A-
3	Rx+	Receive data	BIDB+	Bi-directional data cable B+
4	Reserved	—	BIDC+	Bi-directional data cable C+
5	Reserved	—	BIDC-	Bi-directional data cable C
6	Rx-	Receive data	BIDB-	Bi-directional data cable B-
7	Reserved	—	BIDD+	Bi-directional data cable D+
8	Reserved	—	BIDD-	Bi-directional data cable D-

 

Table 4 RJ-45 MDI-X interface pinouts

Pin	10BASE-T/100BASE-TX		1000BASE-T
	Signal	Function	Signal	Function
1	Rx+	Receive data	BIDB+	Bi-directional data cable B+
2	Rx-	Receive data	BIDB-	Bi-directional data cable B-
3	Tx+	Send data	BIDA+	Bi-directional data cable A+
4	Reserved	—	BIDD+	Bi-directional data cable D+
5	Reserved	—	BIDD-	Bi-directional data cable D-
6	Tx-	Send data	BIDA-	Bi-directional data cable A-
7	Reserved	—	BIDC+	Bi-directional data cable C+
8	Reserved	—	BIDC-	Bi-directional data cable C-

 

To ensure correct communication, the pins for sending data on one port should correspond to the pins for receiving data on the peer port. When both of the ports on the two devices are MDI or MDIX, a crossover Ethernet cable is needed. A cross-over cable connects devices of the same type. When one port is MDI and the other is MDIX, a straight-through Ethernet cable is needed. A straight-through cable connects devices of different types.

The RJ-45 Ethernet interfaces on the router support MDI/MDIX. An MDI/MDIX-autosensing-enabled RJ-45 Ethernet interface can automatically negotiate pin roles. By default, MDI/MDIX is enabled on a port.

Making an Ethernet twisted pair cable

1.     Cut the cable to length with the crimping pliers.

2.     Strip off an appropriate length of the cable sheath. The length is typically that of the RJ-45 connector.

3.     Untwist the pairs so that they can lie flat, and arrange the colored wires based on the wiring specifications.

4.     Cut the top of the wires even with one another. Insert the wires into the RJ-45 end and make sure the wires extend to the front of the RJ-45 end and make good contact with the metal contacts in the RJ-45 end and in the correct order.

5.     Crimp the RJ-45 connector with the crimping plier until you hear a click.

6.     Repeat the above steps with the other end of the cable.

7.     Use a cable tester to verify the connectivity of the cable.

E1 cable

You can use an E1 cable to connect E1-HM96 Ethernet copper ports.

Figure 4 E1 cable (1)

 

Figure 5 E1 cable (2)

 

Figure 6 E1 cable (3)

 

Optical fiber

	CAUTION: Use the same types of transceiver modules, pigtail cords, patch cords, and fiber cables. If you use single-mode optical fibers, the transceiver modules, pigtail cords, patch cords, and fiber cables must be single-mode.

 

Optical fiber

Optical fibers are widely used in fiber-optic communications, which are advantageous for long-distance communications.

Optical fibers can be classified into the following types:

·     Single mode fiber: It has a core size of 10 µm, and has a lower modal dispersion. It carries only a single ray of light. It is mostly used for communication over longer distances.

·     Multi-mode fiber: It has a core size of 50 µm or 62.5 µm or higher, and has a higher modal dispersion than single-mode optical fiber. It is mostly used for communication over shorter distances.

Table 5 Allowed maximum tensile force and crush load

Period of force	Tensile load (N)	Crush load (N/mm)
Short period	150	500
Long term	80	100

 

Optical fiber cable

An optical fiber cable is a cable containing one or more optical fibers. Typically, the optical fiber elements are individually coated with plastic layers and contained in a protective tube. Optical fiber cables contain single-mode and multi-mode optical fiber cables.

Patch cord

A fiber that has connectors at both ends is called a patch cord. A patch cord connects one optical device to another for signal routing. Patch cords contain single-mode and multi-mode patch cords.

·     Single-mode patch cord: The jacket is yellow. It permits transmission over longer distances.

·     Multi-mode patch cord: The jacket is orange. It permits transmission over shorter distances.

Patch cords are mainly classified into SC, LC, and FC patch cords based on interface type. The typical length of a patch cord can be 0.5 m (1.64 ft), 1 m (3.28 ft), 2 m (6.56 ft), 3 m (9.84 ft), 5 m (16.40 ft), and 10 m (32.81 ft).

Pigtail cord

A pigtail cord is an optical fiber that has an optical connector on one end and a length of exposed fiber on the other. The end of the pigtail is fusion spliced to a fiber, connecting the fiber cable and transceiver.

Pigtail cords contain single-mode (yellow) and multi-mode (orange) pigtail cords. Based on interface type, pigtail cords can also be classified into three main types, SC, LC, and FC.

Fiber connector

Fiber connectors are indispensable passive components in an optical fiber communication system. They allow the removable connection between optical channels, which makes the optical system debugging and maintenance more convenient and the transit dispatching of the system more flexible.

Figure 7 LC connector

 

Precautions

·     Make sure the fiber connector and fiber type match the transceiver module type.

·     The optical interfaces on some cards have shielded covers. Remove the shielded covers before using the optical interfaces. Optical interfaces must be installed with shielded covers when they are not in use. Keep them safely.

·     Fiber connectors must be protected under safe and reliable outer packing, and be fitted with dust caps. Fiber connectors must be installed with dust caps when they are not in use. Take care not to scratch their end face. Replace the dust cap if it is loose or polluted.

·     Before connecting a fiber, use dust free paper and absolute alcohol to clean the end face of the fiber connector. You can brush the end face only in one direction. You also need to brush the end face of the other fiber connector.

·     Never bend or curve a fiber when connecting it. After a fiber is installed well, the bend radius must be not less than 40 mm (the minimum dynamic bend radius is 20 D, and the minimum static bend radius is 10 D. D indicates the outer diameter of fiber jackets).

·     If the fiber has to pass through a metallic board hole, the hole must have a sleek and fully filleted surface (the filleting radius must be not less than 2 mm). When passing through a metallic board hole or bending along the acute side of mechanical parts, the fiber must wear jackets or cushions.

·     Insert and remove a plug with care. Never exert a fierce force to the fiber or plug; otherwise the plug might be damaged or the fiber might be broken. Never pull, press or extrude the fiber fiercely. For the allowed maximum tensile load and crush load, see Table 5.