Networks
have the trend to grow, requiring often the need
for repeaters or multiple hubs , where
it is required to follow the rules
on maximum numberof Repeaters/Hubs .This
includes today also the possibility to connect systems
without cables using a WLAN
AccessPoint.
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 expensivein 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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