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Repeaters, Hubs, Bridges and Switches
Networks have the trend to grow, requiring
often the need for repeaters ( on 10base2 - Thin-Ethernet ) or multiple hubs (on 10/100baseT
Twisted-Pair), where it is required to follow the rules on maximum
number of Repeaters/Hubs ( Large Networks: 5-4-3 Rule ).
10base2 - Thin Ethernet (Coax):

10baseT - Twisted Pair (TP/UTP):

But these 'cable-extension' method have all a serious
limitation
concerning the maximum throughput of the network:
(explanation is visually via the animated
GIF below)

Hubs and repeaters are fairly simple, 'non-intelligent'
devices:
whatever comes in on one port, gets amplified and send out to ALL
other ports, so any network transmission 'fills up/flows into'
ALL cable-segments of the network, so only ONE network connection
can be active at a time on the complete network !
When multiple system try to communicate at the same time:
(explanation is visually via the animated
GIF below)

then the signals 'collide'/corrupt each other, making them
invalid, time has been wasted and the system will try after a
random delay again to transmit, resulting in network slowdown.
There is a possibility to optimize such network
configurations:
Bridge:
In the early days of networking, such a 'intelligent'
device called 'Bridge' viewed at
the data inside the transmissions, to find out based on the
Network-card addresses (MAC), whether it is necessary to transmit
the information to a different segment or not. Such Bridges has
only 2 connectors, allowing to split large networks into 2
smaller sub-networks.
Switch:
Switches are also 'intelligent', but are able to handle
more than 2 ports and are able to handle more than 2
communications at the same time:
When a transmission comes in on one port, the switch looks at the
MAC addresses to determine, onto which port to send it out:

Now a large network can handle MULTIPLE transmissions at the same
time:
(explanation is visually via the animated
GIF below)

But to be able to get this additional
Through-put, careful planing of the network layout is required,
looking on the flow of the network traffic:
Singe Server configuration:

Swapping a hub to a Switch in such a configuration will not
optimize the network, since the connection from the TP-HUB to the
server is still the bottle-neck.
Multi Server configuration:

If most the network traffic is within the workgroups
(departments,..) and only few network traffic is between the
workgroups, then a Switch is the solution to optimize network
utilization.
Optimize 10 Mbit Network using a 100 MBit Server
connection:

Blackbox = Hub
if the 'Blackbox' is a hub (even if it is a switching
10/100 Mbit hub), the throughput of the complete network is limited
at 10 Mbit (since ALL traffic
is transmitted by a hub to ALL connected segments and even a 100 Mbit
connection
from the hub to the server results to a very limited improvement
):

Blackbox = Switch
if the 'Blackbox' is a Switch, then each
connected system can communicate at full speed of the
10 Mbit with the server (
because the switch does NOT
pass it through to the other 10 MBit segments and the connection
of 100 MBit with the server can handle the higher throughput)

In reality, a server is handling multiple network
requests at the same time,
which makes the use of a Switch and a 100 Mbit link between the
switch and
the server even more efficient:

Since changing of 10 MBit TP-cabling to 100 Mbit/CAT5-cabling is
expensive
in offices (where cables run inside walls and across sealings),
swapping a
10 Mbit HUB to a 10/100 MBit SWITCH and upgrading the connection
to the
server to 100 Mbit is a cost-effective solution to improve
network throughput.
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