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Follow UsMultimedia on the Internet and GUI based network
applications are very bandwidth hungry. Network managers are trying hard to find
economical ways to provide more network bandwidth. Switches offer a feasible solution by
assuring required bandwidth and alleviating problems like unscheduled downtime faced by
LANs. They also have a remedy for slow or unacceptable response times from file servers.
Switches are devices that filter and forward packets
between LAN segments. They operate at the data link layer (layer 2) of the OSI (Open
System Interconnection, an ISO standard for worldwide communications that defines a
networking framework for implementing protocols in seven layers) Reference Model and
therefore support any packet protocol. LANs that use switches to join segments are called
switched LANs or, in the case of Ethernet networks, switched Ethernet LANs.
A switch intelligently maintains a table, keeping track of
which hardware addresses are located on which network segment. It only sends a packet down
the network segment on which the computer waiting for that packet resides.
How do switches give bandwidth?
Switching technology can provide bandwidth to each port of the switch. If we use a regular
hub, the maximum throughput (for example, 10 MBPS) is shared across all ports of the hub.
That is to say, if the hub has 24 ports the available 10 Mbps is shared across all 24
ports. On the other hand, in a switched networking environment, the switch can dedicate 10
Mbps to each port on the switch, which ensures that maximum bandwidth is available to all
computers on the network.
LAN switching technologies
Two major types of switching technology used in LAN switches exist:
•Cut-through
The cut-through switch reads only the MAC address in each frame's header and immediately
forwards the frame to the destination port. Cut-through switches are not equipped to check
the data for errors. They are best utilized for small workgroup and department
applications.
•Store-and-forward.
Store-and-forward switches wait until the full frame has been received before forwarding
it. This enables it to check incoming data for errors, which can have a devastating impact
on networks, taking up bandwidth with corrupted junk packets. These switches are designed
for enterprise-wide applications.
The bright face of switches
Switching directs network traffic in a very efficient manner. Information is sent
directly from the port of origin, only to its destination port. Network performance is
increased and flexibility is assured.
To carry out its functions efficiently, switches do not
demand modification of software or hardware already running on the workstations.
A switch installation is less complex than a bridge or
router configuration.
Switches are low cost solutions compared to shared
networking devices like bridges, hubs and routers and they provide many of the same
functions.
LAN switches are an easy
and painless path to adding network capacity.
Ethernet Switching
Understand the difference between
networks and get an idea of the basic architecture underlying switch designs.
Switching at every layer
Beware of the media hype
about switches.
Token Ring Switching
Token Ring
Switching has arrived. The advantages of switching apply to this technology as well.
LAN Backbone Switching
Backbone Switching can
provide a solid foundation upon which you can expand a network.
Layer 3 Switching: An Introduction
This paper is a map through the jungle of internetworking infrastructure, particularly
focusing on how Layer 2 switching and Layer 3 routing have combined to form the powerful
architecture.