LAN: A local area network (LAN) is the term used for two or more computers that have been equipped with appropriate hardware and software to allow them to share applications, files and peripherals (modems, printers etc.).
WAN: Wide Area Networks (WANs) are networks with LANs that are
far enough apart to require a telecommunications link between them. In
general, the long distance bandwidth for the WAN is slower then the speed
of the LAN.
2. Name and describe the topologies employed by the "Token Ring"
and "Ethernet" networks.
Token Ring: There are three main topologies: the star, bus, and
ring. A Token Ring network configuration, developed by IBM, carries data
from computer to computer along a ring-shaped network. A token is passed
around the ring, which is sequentially examined by each node on the LAN.
If a node has nothing to send, the token is retransmitted to the next node
in the ring. If a node wants to transmit data, the token is seized, the
data and the MAC address of the destination are added, and the entire packet
is transmitted. The information is passed around the ring until the destination
is reached, and then the node accepts the data. To ensure efficient use
of the bus, some nodes, such as file or print servers, can be given priority
over others.
Ethernet: Another type of network is the Ethernet, one of the
earliest LANs developed in the 1970s. The Ethernet employs the bus layout
where each node is like a station along a main highway. This main highway
is called a segment. This is the medium to which a node is attached. The
highway is shared so that all nodes have equal access to the Ethernet segment
and receive signals at the same time. Nodes gain access to the segment
using a technique called Carrier Sense Multiple Access With Collision Detection
(CSMA/CD). When a node on the Ethernet wants to transmit data, it listens
to see if anybody else is on the network (Carrier Sense). If, it sees no
other traffic it sends the packet. Since all nodes have equal access to
the segment (Multiple Access), sometimes two or more nodes try to transmit
at the same time. If this happens, a collision between the node`s data
will occur. This collision is detected by all nodes (Collision Detection).
Each node then retreats and pauses for a random time interval before transmitting
again. This process continues until the receiver confirms that the transmission
was successful. Like Token Ring, Ethernet uses MAC addresses to indicate
the destination node.
3. Explain why repeaters are called "dumb."
They are called dumb devices, which means they do nothing to change
the data. They merely send an exact copy of what they received from one
LAN to another. They have no intelligence of their own. They simply receive,
amplify, and retransmit data, one bit at a time.
4. Some types of connectors are capable of connecting only networks
with similar topologies while some can connect different types. What connection
capabilities do repeaters, routers and bridges have?
Repeaters: A repeater is used to connect two similar LAN networks, for example Ethernet to Ethernet. The nodes still believe themselves to be on a single LAN. Therefore, in the case of Ethernet, the nodes are in the same collision domain. Repeaters are not capable of connecting together two networks of different technology, for example, Ethernet to Token Ring.
Routers: Unlike the bridge, a router can connect two unlike topologies, such as Ethernet to Token Ring. Routers are generally much more complicated devices and, therefore, cost much more to buy.
Bridges: Bridges are devices used to restrict heavy traffic on a large network by subdividing it into two smaller networks, thus reducing traffic on both sides of the bridge. Reducing the traffic in this way results in better network performance
5. What does it mean when we say bridges "learn?"
When the bridge sees a source MAC address for the first time, it records
which side of the bridge it came from and stores that information for future
use. Eventually, by monitoring traffic, the bridge learns the location
of all the nodes with reference to the ports of the bridge.
6. Explain the Internet Protocol Addressing. Give an example of a
complete address.
IP addressing is used not only to identify the thousands, if not millions
of computers connected to the Internet worldwide, but it is also used in
thousands of private networks. To ensure that numbers are assigned to only
one network or company, an organization called the Network Information
Centre (NIC) was established to issue and maintain records of all IP addresses.
IP addresses are made up of 32 bits, which are divided into four 8-bit octets and presented in a dotted decimal notation format. An example of an IP address is 200.20.10.8. The four octets are divided into network identifier and a host identifier.
Network identifiers are broken into classes. The 3 classes of networks
are A, B, and C. A class A address is any address that begins with the
numbers 1 to 126, such as 90.1.3.4. The first octet of an assigned address
will never change, but the owner of that address may do whatever he likes
with the last three octets. The 24 bits available in the last 3 octets,
are the host addresses. A class A address may have over 16 million hosts
on the one network. This class is only assigned to very large organizations.
7. Surf the Internet and find examples of the following site addresses:
Find:
One example of a top level name that indicates it is a commercial business.
Three examples of top level names that indicates they are from a different
country.