Interfaces and cables
Last updated
Last updated
collection of network protocol/standards
RJ45 - Registered Jack - used at the end of copper ethernet cable (UTP)
agreed upon system of communicating
to make the switch and cable manufacturer to agree upon the size and shape of the connector and port
all vendors follow industry standards
physical standards - connectors and cables
logical standards - internet protocol (IP)
1 byte = 8 bits
speed is measured in bits/second (mbps-megabits/s, not bytes)
data in hard-drive is measured in bytes
Unshielded Twisted Pair
copper cables used in ethernet standards
4 pairs of cables twisted together
uses separate wire pairs "within the cable" to transmit and receive data
no metallic shield
vulnerable to electrical interference
10mbps
Ethernet
802.3i
10BASE-T
100mbps
Fast ethernet
802.3u
100BASE-T
1gbps
Gigabit ethernet
802.3ab
1000BASE-T
10gbps
10 gig ethernet
802.3an
10GBASE-T
BASE - baseband signalling T - twisted pair cabling (max length = 100m) twists helps protect from Electro Magnetic Interference (EMI)
uses 2 pairs - 4 wires
Scenario 1: connection between PC/router/firewall and switch
PC/firewall/routers Transmit (TX) data on pins 1&2 and Receive (RX) data on pins 3&6
Switches Receive (RX) data on pins 1&2 and Transmit (TX) data on pins 3&6
Straight-through cable - used when connecting devices which use opposite pin pairs to transmit and receive data
Full-duplex transmission - both devices can send and receive data at the same time with no collisions
Scenario 2: connection between router&router or switch&switch or router&PC
Crossover cable - used when connecting devices which use same pin pairs to transmit and receive data
pins 1&2 of device A are connected to pins 3&6 of device B
pins 3&6 of device A are connected to pins 1&2 of device B
allows devices to automatically detect which pins their neighbor is transmitting data on, and then adjust which pins they use to transmit and receive data
unless working with old equipment, need not worry about straight-through or crossover cables
uses 4 pairs - 8 wires
each pair is bidirectional (no specific pins for transmitting and receiving), thus can operate at much higher speeds
apart from already used pins, pins 4&5, 7&8 are connected straight
Fiber optic cables send light over glass fibers, rather than electrical signal over copper wires
SFP (Small Form-factor Pluggable) transceiver is connected to switches or routers
fiber optic cables connect to these transceivers
there are 2 connectors on each end, one to transmit and another to receive data
unlike copper UTP cables which use wire pairs within the cable, fiber optic cables use separate cables to transmit and receive
Transmit (Tx) pin on A connects to Receive (Rx) pin on B and vice versa.
fiberglass (core)
cladding (reflects light)
protective buffer
outer jacket
Multi-mode fiber cables
core diameter is wider
allows multiple angles (modes) of light waves to enter the fiberglass core
allows longer cables than UTP, but shorter than single-mode fiber
cheaper than single-mode fiber (due to cheaper LED-based SFP transmitters)
Single-mode fiber cables
core diameter is narrower
light enters at a single angle (mode) from a laser-based transmitter
allows longer cables than UTP and multi-mode fiber
more expensive because it uses laser-based SFP transmitters)
1000BASE-LX
802.3z
1gbps
multi or single mode
550m(MM) 5km(SM)
10GBASE-SR
802.3ae
10gbps
multi mode
400m
10GBASE-LR
802.3ae
10gbps
single mode
10km
10GBASE-ER
802.3ae
10gbps
single mode
30km
Most hosts do not have the capability to connect to a switch via fiber cabling, and most switches do not have enough SFP interfaces to support many end hosts. UTP cables are the standard for wired connections to switches. Switches typically have many RJ45 ports for end hosts to connect to via UTP cable, and then connect to a router with the SFP fiber optic port.