Intel 460T - Manual (Page 18)

12
C H A P T E R 2 Intel Express 460T Standalone Switch Users Guide
What is a Switch?
A switch segments traffic, providing each port its own collision domain. This
is different from a hub where all ports belong to the same collision domain.
Segments and Hubs
Hubs combine multiple wires so all attached devices behave like they are on
the same wire. Because the devices share the same segment, data sent by
one device is retransmitted to all devices on the same hub. This is equivalent
to having all devices connected in a bus topology as illustrated below.
Client A sends
signal to Client B
Client B
receives signal
Client A Client B Signal sent to all ports
The disadvantage is all devices must share the total available bandwidth.
The more devices that are attached to the hub the less bandwidth for each
user. Also, network performance suffers because all devices receive traffic
and collisions from other users as the hub retransmits data across all ports.
Switches
Switches send traffic only to specific ports, rather than transmitting data
across all ports. This means that each device attached to the switch receives
fewer collisions and the entire bandwidth is available to the device.
Client A sends
signal to Client B
Client B
receives signal
The signal is not
sent to all ports
MAC Address Port
006011FB34DB 2
00A027D36FAA 8
The switch maintains a table that associates a device’s MAC address to a
port on the switch. When Client A communicates with Client B, the switch
checks the table to determine which port Client B is attached to and then
forwards the traffic to that port. If a device sends traffic to an address that is
not in the table (or sends broadcast or multicast traffic) the switch sends the
traffic out to all ports on the switch. When the switch receives a response it
updates the table with the new address.