3. FUNCTIONS
• A Hub is a networking device
which receives signal from the
source, amplifies it and send it
to multiple destinations or
computers. If you ever some
across subject 'Computer
Networking' then you must
heard this word. Sometimes,
hubs are also called Ethernet
Hub, Repeater Hub, Active Hub
and Network Hub. Basically it is
a networking device which is
used multiple devices like
Computers, Servers etc to each
other and make them work as a
single network segment. Hubs
are used in 'Physical Layer' of
OSI Model.
4. CONSTRUCTION
• Practically Hubs is a small box in rectangular shape which have multiple
ports for connecting various devices to it. It receives its power supply
from auxiliary power sources. The main work of Hub is to receive
incoming data signals, amplify them in the form of electrical signals and
then send them to each connected device. A Hub may contain a number
of ports. Minimum amount of ports that a hub can have is 4 and it can
have up to 24 ports for connecting various devices and peripherals to it.
• Types of Hub:On the basis of its working methods, the Hubs can be
divided into three types, given as:
• Active Hub
• Passive Hub
• Intelligent Hub
6. FUNCTIONS
• A network switch (also called switching hub, bridging hub,
officially MAC bridge[1]) is a computer networking device that
connects devices together on a computer network, by using
packet switching to receive, process and forward data to the
destination device. Unlike less advanced network hubs, a network
switch forwards data only to one or multiple devices that need
to receive it, rather than broadcasting the same data out of
each of its ports.
• A network switch is a multiport network bridge that uses
hardware addresses to process and forward data at the data
link layer (layer 2) of the OSI model. Switches can also process
data at the network layer (layer 3) by additionally incorporating
routing functionality that most commonly uses IP addresses to
perform packet forwarding; such switches are commonly known
as layer-3 switches or multilayer switches.[3] Beside most
commonly used Ethernet switches, they exist for various types
of networks, including Fibre Channel, Asynchronous Transfer
Mode, and InfiniBand. The first Ethernet switch was introduced
by Kalpana in 1990.
7. DESIGN
• An Ethernet switch operates at the data link layer (layer
2) of the OSI model to create a separate collision
domain for each switch port. Each device connected to a
switch port can transfer data to any of the other ones
at a time, and the transmissions will not interfere – with
the limitation that, in half duplex mode, each switch
port can only either receive from or transmit to its
connected device at a certain time. In full duplex mode,
each switch port can simultaneously transmit and
receive, assuming the connected device also supports
full duplex mode.
• In the case of using a repeater hub, only a single
transmission could take place at a time for all ports
combined, so they would all share the bandwidth and run
in half duplex. Necessary arbitration would also result in
collisions, requiring retransmissions.
9. FUNCTION
• A router[a] is a networking device that forwards data packets between
computer networks. Routers perform the traffic directing functions on
the Internet. A data packet is typically forwarded from one router to
another through the networks that constitute the internetwork until it
reaches its destination node.
• A router is connected to two or more data lines from different networks.
[b] When a data packet comes in on one of the lines, the router reads the
address information in the packet to determine the ultimate destination.
Then, using information in its routing table or routing policy, it directs the
packet to the next network on its journey. This creates an overlay
internetwork.
• The most familiar type of routers are home and small office routers that
simply pass IP packets between the home computers and the Internet. An
example of a router would be the owner's cable or DSL router, which
connects to the Internet through an Internet service provider (ISP).
More sophisticated routers, such as enterprise routers, connect large
business or ISP networks up to the powerful core routers that forward
data at high speed along the optical fiber lines of the Internet backbone.
Though routers are typically dedicated hardware devices, software-based
routers also exist.
10. • A router has two stages of operation called planes
• Control plane: A router maintains a routing table that lists which route should be
used to forward a data packet, and through which physical interface connection. It
does this using internal pre-configured directives, called static routes, or by learning
routes using a dynamic routing protocol. Static and dynamic routes are stored in the
Routing Information Base (RIB). The control-plane logic then strips non essential
directives from the RIB and builds a Forwarding Information Base (FIB) to be used
by the forwarding-plane.
• Forwarding plane: The router forwards data packets between incoming and outgoing
interface connections. It routes them to the correct network type using information
that the packet header contains. It uses data recorded in the routing table control
plane.
• Routers may provide connectivity within enterprises, between enterprises and the
Internet, or between internet service providers' (ISPs) networks. The largest
routers (such as the Cisco CRS-1 or Juniper T1600) interconnect the various ISPs, or
may be used in large enterprise networks.[6] Smaller routers usually provide
connectivity for typical home and office networks. Other networking solutions may
be provided by a backbone Wireless Distribution System (WDS), which avoids the
costs of introducing networking cables into buildings.
12. INTRODUCTION
• A network bridge, also known as an
Ethernet bridge, connects two segments
of a network together. The segments
are not independent entities, but are
owned and managed by the same
organization. The purpose of the bridge
is to divide a network into manageable
sections.
13. COLLISION
• A network connects a number of computers together
with one cable. The data passed over the cable is an
electronic pulse that travels the length of the wire.
More than one message pulsing on the cable would
merge and interfere with each other. Only one device
can transmit at any one time. If a network connects a
large number of computers, each would have to wait a
long time to get a turn applying data to the line. The
main reason for segmenting networks is to reduce the
number of devices connected to the same wire and
thus reduce the wait time for transmission. A
network bridge unites these segments.
14. INSTALLATION
• Bridges operate with MAC addresses. On
being introduced to a network, the bridge
learns the MAC addresses of the devices on
each segment to which it connects. It then
keeps a table of these locations. The MAC
address is the physical address of a computer
and is hard-coded onto the computer's
network adapter.
15. OPERATION
• Once the bridge has compiled its filtering table
it operates by listening to the data packets
traveling on each segment. If it receives a data
packet where the source and destination
addresses are on the same segment, it ignores it.
This is called ''filtering." If the source and
destination of the packet are on different
segments, it passes the packet through to the
segment containing the destination computer.
18. INTRODUCTION
• A bridge router or brouter[1] is a network device that works as
a bridge and as a router. The brouter routes packets for known
protocols and simply forwards all other packets as a bridge
would.[2]
• Brouters operate at both the network layer for routable
protocols and at the data link layer for non-routable protocols.
As networks continue to become more complex, a mix of
routable and non-routable protocols has led to the need for the
combined features of bridges and routers. Brouters handle both
routable and non-routable features by acting as routers for
routable protocols and bridges for non-routable protocols.
Bridged protocols might propagate throughout the network, but
techniques such as filtering and learning might be used to
reduce potential congestion. Brouters are used as connecting
devices in the networking system, so it acts as a bridge in a
network and as a router in an internetwork.
19.
20. IP ADDRESS
• An Internet Protocol address (IP address) is a numerical label assigned
to each device (e.g., computer, printer) participating in a computer
network that uses the Internet Protocol for communication.[1] An IP
address serves two principal functions: host or network interface
identification and location addressing. Its role has been characterized
as follows: "A name indicates what we seek. An address indicates where
it is. A route indicates how to get there."[2]
• The designers of the Internet Protocol defined an IP address as a 32-
bit number[1] and this system, known as Internet Protocol Version 4
(IPv4), is still in use today. However, because of the growth of the
Internet and the predicted depletion of available addresses, a new
version of IP (IPv6), using 128 bits for the address, was developed in
1995.[3] IPv6 was standardized as RFC 2460 in 1998,[4] and its
deployment has been ongoing since the mid-2000s.
• IP addresses are usually written and displayed in human-readable
notations, such as 172.16.254.1 (IPv4), and 2001:db8:0:1234:0:567:8:1
(IPv6).
21. TYPES OF IP
CLASS Range Of IP No. Of Hosts
Bits Free For
Change By Host
A:- Governments 0-127 16,777,216 3
B:- Big Companies 128-191 65,536 2
C:- Small
Companies
192-223 256 1
D:- Multicast Grp. 224-239 N.A. N.A.
