3Com 3C16440 - SuperStack II Baseline Hub 12 Scheda tecnica - Pagina 2
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Hubs
Hubs are the most basic building
blocks for connecting together your
PCs, servers, and peripherals to form
a network. Sometimes referred to as
repeaters, hubs allow the attached
network devices to communicate with
each other and share information.
Connections to hubs are often referred
to as shared media connections, such as
shared 10 or shared 100, as opposed to
switched connections.
There are two types of hub in
the SuperStack II Baseline family:
The Baseline Hub, which
communicates with other network
devices at a speed of 10 Mbps;
The Baseline Dual Speed Hub,
which is capable of communicating
with other network devices at up
to 100 Mbps.
Both are available in 12- and 24-port
variants.
The right choice for you will depend
on the performance you need and the
speed at which your network devices
are capable of running. If some of your
PCs, servers, and network peripherals
are capable of running at 100 Mbps,
you will benefit from the tremendous
performance increase of the Baseline
Dual Speed Hub.
According to ISO/IEEE standards,
there is a limit to the number of hubs
that can be connected in series.
For 10 Mbps, the limit is four; for
100 Mbps, the limit is two.
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Switches
Why would you need a switch?
Although they provide the same
connectivity for your network cables
as hubs, switches give you far superior
network performance. They do this by
increasing the network's available data
bandwidth (the maximum capacity of
the network for moving data). Instead
of sharing the total available bandwidth
among all connected users, as a hub
does, a switch gives each attached
network device its own dedicated
amount of bandwidth.
For example, any 10 Mbps hub
will offer 10 Mbps of bandwidth to
be shared among all devices attached
to it. An equivalent switch will offer
10 Mbps of bandwidth for exclusive use
by each attached device. Performance
will be much faster. It is further
increased if the switch supports full-
duplex links like the Baseline switches.
Switches operate by learning the unique
MAC address of each network device on
your LAN, and by knowing which port
each one is connected through.
There are two types of switches in the
SuperStack II Baseline family:
The Baseline Switch communicates
with other network devices at a
speed of 10 Mbps, and has two
10/100 Mbps links capable of run-
ning at 100 Mbps for fast links to
servers or the network backbone;
The Baseline 10/100 Switch,
is capable of communicating
with other network devices at up
to 100 Mbps on all ports for the
ultimate in high-speed connectivity.
Both are available in 12- and 24-port
variants.
Switches are most suited to certain
applications:
Near the core of the network,
they eliminate bottlenecks and
improve the overall network
throughput;
They can extend the span of a
network that has the maximum
allowed hubs connected in series;
When used as a desktop
connectivity device, they provide
the highest possible performance
for connecting users to your
network.
10/100 Mbps
(Dual Speed) Operation
Today, more and more PCs, servers,
and network peripherals that you buy
have the capability to connect to either
a 10 Mbps or 100 Mbps network link.
They can operate up to 10 times the
speed of traditional 10 Mbps links as
long as the hubs or switches they are
connected to can support 100 Mbps
operation. Why waste this latent
performance by connecting them
to a network device running at only
10 Mbps?
Your concern might be that you have
some older PCs, printers, or peripherals
that have a 10 Mbps-only network
connection. You will probably not
want to upgrade all of these at once to
connect to 100 Mbps hubs or switches.
In fact, some of your legacy devices may
not upgrade from 10 Mbps.
So, how can you connect some
devices into your hubs and switches
at 10 Mbps and some at 100 Mbps?
How do you ensure that you don't
connect them at the wrong speed?
By using a dual-speed hub or a switch
with 10/100 Mbps links on every port,
they will communicate with connected
equipment at either 10 Mbps or
100 Mbps as appropriate.
After installing a dual-speed hub
or a 10/100 Mbps switch, you can
gradually and seamlessy migrate
your network to run at 10 times the
speed! You can add newer, high-speed
network devices or upgrade your
existing equipment as the need
arises (and your budget allows).
The SuperStack II Baseline family
includes:
The Baseline Dual Speed Hub; and
The Baseline 10/100 Switch
Both are autosensing. They will link up
with your network users at 100 Mbps, if
possible, otherwise, they will instantly
and automatically revert to running at
10 Mbps. They always ensure that your
network runs as fast as your users are
capable. There's no need to worry about
patching a PC or a server to a hub or
switch at the wrong speed—and no
need to worry about whether you're
wasting valuable network bandwidth.