Network and Telecommunication Cables
First, the fundamentals: Below is an ANSI/TIA/EIA-422-B (formerly RS-422) or ITU-T V.35 serial cable for connecting a Cisco router's serial port to a T1/DS1 interface.
The V.35 interface is now specified as ITU-U V.11. V.35/V.11 is for data communication at speeds up to 10 Mbps.
This type of cable has a DB-60 connector at the router end, and a Winchester block connector at the network interface end. Cisco's description, including pinouts, is here.
At left is one end of a Category 5 Ethernet cable, or more formally, ANSI/TIA/EIA-568-A.
The connector is informally known as an RJ45. To be pedantic, that's incorrect: it is really an 8P8C modular connector.
Why is "RJ45" incorrect? The RJ45 standard refers to the physical connector and the wiring pattern. A true RJ45 was used for an analog telephone connection and was intended for use with a high-speed modem. Pins 5 and 4 were the tip and ring, respectively, of a single telephone line, and pins 7 and 8 were a programming resistor.
The wiring of a true 8P8C connector is:
|Pin||EIA T568A||EIA T568B|
|Wire, of pair||Color||Wire, of pair||Color|
|1||1 of 3||white/green||1 of 2||white/orange|
|2||2 of 3||green||2 of 2||orange|
|3||1 of 2||white/orange||1 of 3||white/green|
|4||2 of 1||blue||2 of 1||blue|
|5||1 of 1||white/blue||1 of 1||white/blue|
|6||2 of 2||orange||2 of 3||green|
|7||1 of 4||white/brown||1 of 4||white/brown|
|8||2 of 4||brown||2 of 4||brown|
|To make a crossover cable, wire one end as T568A and the other as T568B.|
Right to left in the picture above, or top to bottom in the picture below, are pins 1 through 8.
10BASE-T (Ethernet) and 100BASE-TX (Fast Ethernet) use wire pairs 2 and 3, or wires 1/2 and 3/6.
10BASE-T uses two differential voltages: +2.5V or -2.5V, signalling at 10 Mbaud.
|Electrical characteristics for Cat.5e|
|Impedance at 100 MHz||100±15Ω|
|Capacitance at 800 Hz||52 pF/m|
|Propagation delay||4.8-5.3 ns/m|
100BASE-TX uses three differential voltages: +1V, 0V or -1V. 4B5B binary encoding generates a signal clocked at a 125 MHz symbol rate. Data bits are grouped into groups of 4 bits each, each data block converted to a 5-bit block guaranteed to have at least two transistions and solve problems of receiver clock synchronization, DC equalization, and spectrum shaping.
1000BASE-T (Gigabit Ethernet) uses all four wire pairs, signaling with 5-level pulse amplitude modulation at a 125 Mbaud symbol rate.
|5, 5e||100 MHz|
All these standards should be able to communicate over cables up to 100 meters long. Cables are rated in terms of their RF bandwidth rather than supported bit rate, as listed in the table at right.
The wire pairs are twisted together to create a bundle of balanced transmission lines and reduce crosstalk between pairs. The twisting is at 1.5-2 cm per turn.
The wires are #24 AWG or 0.205 mm², rated for 0.577 A maximum current.
At right and immediately below, Category 5 Ethernet cables plugging into a bank of Cisco switches, along with four fiber optic lines (smaller diameter yellow and orange lines).
Above are fiber optic network connections.
At right are ANSI/TIA/EIA-422-B serial connections to three Cisco routers.
At left and below are a Fujitsu FLM 600 MD / 2400 LS OC-12 SONET ring and FLM-150 SONET interfaces.
Above at left is a Tsunami 100 5.3/5.8 GHz wireless Ethernet bridge mounted above a Cisco Catalyst 2950 switch with 24 Ethernet ports and two fiber ports,
Below is an ATM switch at left and a Cisco Catalyst 48-port Ethernet switch.
At right and below are DS3 and OC3 router interfaces on a Lucent Packetstar AX 600 and a Cisco 7204.
At left and below are some telecommunications punchdown blocks.
The panel at left is relatively simple and widely spaced as these things go.
The large panel shown overall and in detail below is at a major conference center.
Finally, here is a random collection of dangling Ethernet and fiber lines:
If you like this, make sure to see my page showing the telecommunications infrastructure in Manhattan.