Interfaces and Cables

Bits and bytes

● 1 kilobytes (kb) = 1, 000 bits

● 1 megabits (mb) = 1,000,000 bits

● 1 gigbits (gb) = 1,000,000,000 bits

● 1 terabit (tb) = 1,000,000,000,000 bits

Ethernet Standards

● Defined in the IEEE 802.3 standard in 1983.

● IEEE = Institute of Electrical and Electronics Engineers

802.3i

Speed: 10 mbps

Common name: Ethernet

Informal name: 10base-t

Max Length: 100 m

Pairs: 2 pairs ( 4 wires)

802.3u

Speed: 100

Common name: Fast Ethernet

Informal Name: 100base-T

Max lenght: 100m

Pairs: 2 pairs ( 8 wires)

802.3ab

Speed: 1 gbps

Common name: Gigabit Ethernet

Informal name: 1000base-T

Max lenght: 100m

Pairs: 4 pairs (8 wires)

802.3an

Speed: 10 gbps

Common name: 10 Gig ethernet

Informal name: 10gbase-T

Max lenght: 100m

Pairs: 4 pairs ( 8 wires)

UTP

Unshielded Twisted Pair: It protects against EMI (Electromsgnetic Interference)

UTP Cables (10base- T , 100base-T)

Straight-through cable

Transmit (Tx) on pin 1 and 2 ( PC , Router) Switch Receive on those pin

Receive (Rx) on pin 3 and 6 (PC, Router) switches Transmit on those pins

UTP Cables (10base- T , 100base-T) Crossover cable

Crossover cable

Transmit (Tx) on pin 1 to 3, 2 and 6 when connect two switches(Routers/PC)

Receive (Rx) on pin 3 to 1, 6 to 1, when connect two switches(Routers/PC)

When use switches with auto MDI-X

UTP cables pin tables (10Base-T, 100Base-T)

Device: Router uses pin 1&2(tx), 3&6(rx)

Device: Firewall same as Router

Device: PC. Same as Router

Device: Switch pin 3&6(tx), 1&2(rx)

SFP transceiver

Small form-facter pluggable

Fiber-Optic Connection

1: the fiberglass core itself

2: cladding that reflects light

3: a protective buffer

4: the outer jacket of the cable

Multimode Fiber

● Core diameter is wilder than single-mode fiber.

● Allows multiple angles (modes) of light waves to enter the fiberglass core.

● Allows longer cables that UTP, but shorter cables than single-mode fiber.

● Cheaper than single-mode fiber (due to cheaper LED-based SFP tranmitters)

Single-mode fiber

● Core diameter is narrower that multimode fiber.

● Light enters at a single angle (mode) from a laser-base transmitter.

● Allows longer cables that both UTP and multimode fiber.

● More expensive than multimode fiber ( due to more expensive laser-based SFP transmitters)

1000Base-LX

Stardard: 802.3z

Speed: 1 Gbps

Type: Multimode or Singlemode

Max length: 550m (MM) and 5km (SM)

10GBase-SR

Standard: 802.3ae

Speed: 10Gbps

Type: Multimode

Max length: 400m

10GBase-LR

Standard: 802.3

Speed: 10 Gbps

Cable type: Single-mode

Max lenght: 10 km

10GBase-ER

Standard: 802.3ae

Type: Single mode

Speed: 10 Gbps

Max lenght: 30 km

UTP cost

● Lower cost than fiber-optic

● Shorter maximum distance than fiber-optic (~100m).

● Can be vulnerable to EMI ( Eletromagnetic interference)

● RJ45 ports used with UTP are cheaper than SFP ports.

● Emit (leak) a faint signal outside of the cable, which can be copied (-security risk)

Fiber-Optice

● Higher cost that UTP

● Longer maximum distancecthat UTP

● No vulnerability to EMI.

● SFP ports are more expensive that RJ45 ports ( single-mode is more expensive than multimode)

● Does not emit any signal outside of the cable (=no security risks).