- Broadcasting:
- Broadcasting = transmission is received by all receivers
- There are 2 types of
broadcast networks:
- Wireless (broadcast) networks
Examples:
- Aloha (first wireless network)
- IEEE 802.11 networks (popularly knowns as "Wifi" networks)
- BlueTooth
- Wired broadcast networks
Example:
- Ethernet (popular in the US)
- Token ring (popular in Europe)
- Token bus
- Wireless (broadcast) networks
- Different varieties
of Ethernets:
(they all use the same protocol)
- 10-Base 2 (10 Mb/s --- a.k.a.
"Thin" Ethernet --- uses
a coaxial cable)
- 10-Base T (10 Mb/s Ethernet --- uses a CAT5 cable)
- 100-Base T (100 Mb/s Ethernet or "Fast Ethernet" --- click here))
- 1000-Base T (1 GBs Ethernet or "Gigabit Ethernet" --- click here)
- 10-Base 2 (10 Mb/s --- a.k.a.
"Thin" Ethernet --- uses
a coaxial cable)
- Connectors used by
Ethernet:
The left connector is a CAT5 cable connector.
The right connector is a Coaxial cable connector.
- Cables used in Ethernet:
- Coaxial cable:
- CAT5 (Category 5) cable:
Wikipedia page: click here
- Coaxial cable:
- Ancient way to
connect Ethernet ---
using "Thin" Ethernet:
(coaxial cable,
a.k.a.: 10Base2 Ethernet)
- Modern Architecture of an Ethernet:
(uses a Ethernet hub)
The Ethernet (repeating) hub will repeat an incoming message on some port on all other ports:
(The arrows represent the transmission forwarding)
- Advantage:
- Simple (cheap) hardware
- The "Thin" Ethernet uses a coaxial cable to connect the computers !!!
- No routing
(= finding a
route/path to the
destination)
- Because every message transmissions will reach all computers !!!
- Simple (cheap) hardware
- Disvantages:
- Excessive processing overhead:
- A message transmission is
received by
every
Ethernet hosts (computer)
- Including the hosts that are not the destination of the message !!!!
- Every host
must
determine whether
the message was
destined for the
host (or not)
Result:
- excessive processing overhead
- A message transmission is
received by
every
Ethernet hosts (computer)
- Not Scalable
- When 2 or more
computers transmit
at the same time,
the
transmissions
will be corrupted:
- Result:
- Broadcast networks
(such as Ethernet) can
only support a
limited number of
computers
- Because if you have a large number of computers, the probability that 2 or more of them will transmit at the same time is increased.
(Max ~500 hosts on one Ethernet network)
- Broadcast networks
(such as Ethernet) can
only support a
limited number of
computers
- When 2 or more
computers transmit
at the same time,
the
transmissions
will be corrupted:
- Excessive processing overhead: