First of all what is CCNA means CISCO CERTIFIED NETWORK ASSOCIATE .
So start first chapter the name of first chapter NETWORK FUNDAMENTAL
Network mean the group of electronic device connected with each other called Network .
Networking mean Sharing and Resources of information is Networking with the help of data and the group of computer are connect and sharing data to each other its called networking
LAN is a computer network that interconnect computer in a limited area such as a home, school, computer laboratory or office building using network media .
MAN is a computer network that usually spans a city on a large campus. A Man usually interconnect a number of local area network using a high capacity backbone technology such as fiber optical links . a man organized b/w a city is called MAN .
WAN Network are organized within a city is called WAN.and is a telecommunication network that cover a broad area any network that link across Metropolitan , Region and national boundaries is called WAN.
· Explaining network topology
Exploring LANs, WANs, and MANs
·
Reviewing subnet masks
·
Networking, especially the subset of networking that involves routing and switching using Cisco Systems,
Inc. equipment and software, has a language all its own. In fact, most of this book is dedicated to teaching you
first the language of the CCNA s world, along with the tools of the trade. However, in this chapter, we want
to provide you with an overview of the terminology and concepts that are fundamental to all of networking,
including Cisco networks.
Laying Out the Network Topology
Remember Topology is the physical layout of the computer, other nodes and cabling of the network. For the
exam, you re expected to know the most common types of network topologies.
Please accept our topologies
Local area networks are constructed in a physical layout form that best suits the network s location, the
building, and where its nodes are located. Most LANs are laid out in a general shape and pattern that
facilitates the connection of workstations and other devices to the network. This general shape and pattern is
referred to as the network s topology.
There are four general network topologies:
Bus: Nodes are connected to a central cable, called a backbone, which runs the length of the network.
A bus network topology.
Ring: The primary network cable is installed as a loop, or ring, and the workstations are attached to
the primary cable at points on the ring.
Star: Each workstation connects directly to the central server with its own cable, creating a
statesmanlike pattern.
Mesh: Each workstation connects directly to the server and all other workstations, creating a mess, I
mean, mesh of network connections. This topology is not very common actually, but it is mentioned
on the test.
Mixed topologies
The star topology is more commonly used today to cluster workstations on bus or ring networks. This creates hybrid or mixed topologies, such as the star−bus and the star−ring (also called the ringed−star):
Star−bus: A very common implementation for Ethernet networks. A hub or switch is used as the
central or clustering device that is then attached to the network backbone (see Figure 2−3). This is the
most common topology of Ethernet networks.
Star−ring: Used with ring (Token Ring) networks. A special type of hub, called a multistation access unit (MSAU), is used to cluster workstations and to connect to the next MSAU on the network to
complete the ring. Instead of using a pure ring structure, the star−ring is the most common form of
ring networks.
A ring network topology.
A local area network.
A wide Area Network
So start first chapter the name of first chapter NETWORK FUNDAMENTAL
Network mean the group of electronic device connected with each other called Network .
Networking mean Sharing and Resources of information is Networking with the help of data and the group of computer are connect and sharing data to each other its called networking
LAN, MAN and WAN
LAN mean local area network
MAN mean Metropolitan area Network
WAN mean Wide area Network
LAN is a computer network that interconnect computer in a limited area such as a home, school, computer laboratory or office building using network media .
MAN is a computer network that usually spans a city on a large campus. A Man usually interconnect a number of local area network using a high capacity backbone technology such as fiber optical links . a man organized b/w a city is called MAN .
WAN Network are organized within a city is called WAN.and is a telecommunication network that cover a broad area any network that link across Metropolitan , Region and national boundaries is called WAN.
OSI
Reference Model
A major part of
the CCNA exam focuses on your knowledge of the OSI Reference Model and its
seven−layer approach to network activities,
functions, data formats, and communications. Of course, there is moreemphasis in those layers of the
model that deal with routing and routers, but every layer in the reference
model is included on the exam. As
you prepare for the exam, be sure this is an area you know and understand
in detail.
WAN
protocols
Routers are more often used to
connect local area networks (LANs) to other networks than as an interior
device on a single network.
Because of this, the protocols used to carry data and control signals over wide
area networks also have an
emphasis on the CCNA exam. This part of the test focuses on Frame Relay, X.25,and point−to−point protocols,
along with ISDN services.
Cisco
IOS commands
The commands used to configure
and monitor router activities play a key part in the everyday life of a
CCNA. For that reason, the CCNA
exam includes a number of questions on the configuration modes used forthe various commands and the
methods and sources used to load and back up the IOS software and the
router_s configuration.
Network
protocols
Cisco routers must be able to
interface with network protocols to properly interact with a network. On the
CCNA exam, Ethernet and TCP/IP
protocols are the primary focus reflecting the most popular network
architectures in use in the real
world. You need to know which network protocols are used on which layers of the OSI model and when and how
the IP and IPX protocol suites are applied.
Routing
You must know the difference
between a routed protocol and a routing protocol, including some examples
and configuration methods.
Internetworking issues are also included in this portion of the exam.
Network
security
This section of the CCNA exam is
concerned with passwords, encryption, and access lists implemented on
the router, including how access
lists are configured and operate under either IP or IPX protocol suites.
LAN
switching
The other emphasis on the CCNA
exam, beyond routing, is switching. One of the major emphasis areas of
this section of the exam is LAN
segmentation, including its benefits and how it is accomplished with routers,
bridges, and switches.
Exploring LANs, WANs, and MANs
·
Reviewing subnet masks
·
Networking, especially the subset of networking that involves routing and switching using Cisco Systems,
Inc. equipment and software, has a language all its own. In fact, most of this book is dedicated to teaching you
first the language of the CCNA s world, along with the tools of the trade. However, in this chapter, we want
to provide you with an overview of the terminology and concepts that are fundamental to all of networking,
including Cisco networks.
Laying Out the Network Topology
Remember Topology is the physical layout of the computer, other nodes and cabling of the network. For the
exam, you re expected to know the most common types of network topologies.
Please accept our topologies
Local area networks are constructed in a physical layout form that best suits the network s location, the
building, and where its nodes are located. Most LANs are laid out in a general shape and pattern that
facilitates the connection of workstations and other devices to the network. This general shape and pattern is
referred to as the network s topology.
There are four general network topologies:
Bus: Nodes are connected to a central cable, called a backbone, which runs the length of the network.
A bus network topology.
Ring: The primary network cable is installed as a loop, or ring, and the workstations are attached to
the primary cable at points on the ring.
Star: Each workstation connects directly to the central server with its own cable, creating a
statesmanlike pattern.
Mesh: Each workstation connects directly to the server and all other workstations, creating a mess, I
mean, mesh of network connections. This topology is not very common actually, but it is mentioned
on the test.
Mixed topologies
The star topology is more commonly used today to cluster workstations on bus or ring networks. This creates hybrid or mixed topologies, such as the star−bus and the star−ring (also called the ringed−star):
Star−bus: A very common implementation for Ethernet networks. A hub or switch is used as the
central or clustering device that is then attached to the network backbone (see Figure 2−3). This is the
most common topology of Ethernet networks.
Star−ring: Used with ring (Token Ring) networks. A special type of hub, called a multistation access unit (MSAU), is used to cluster workstations and to connect to the next MSAU on the network to
complete the ring. Instead of using a pure ring structure, the star−ring is the most common form of
ring networks.
A ring network topology. A local area network.
A wide Area Network
Subnet
Mask Review
Remember
There are three usable IP address classes: Class A, Class B, and Class C. Two
other IP address
classes
do exist, but they_re set aside for special purposes. Each IP address class (A,
B, and C) has a finite
number
of bits assigned to hold each of the network and host IDs. Table 2−1 lists the
number of bits
designated
for each of these identities in the 32−bit IP address.
Class of Network Bits of Host Bits
No
of Network Number
Of Host Bits
A 8 24
B 16 16
C 24 8
Whether
or not a destination address is located on the local network must be decided
without consideration to the IP address class of the network. For any subnetted
network, a subnet mask can be applied to extract the network ID from the
destination address. The network ID can then be compared to the local network
ID and the message routed accordingly. To make this determination, every IP
address must have a subnet mask.
Class
Decimal Mask Binary Mask
A
255.0.0.0 11111111 00000000 00000000 00000000
B
255.255.0.0 11111111 11111111 00000000 00000000
C
255.255.255.0 11111111 11111111 11111111 00000000
Remember The CCNA exam asks you to provide at least
three reasons that the _industry_ uses layered
interconnection models. First, here are some basic
definitions. A layered model is one that takes a task, such
as data communications, and breaks it down into a
series of tasks, activities, or components. Examples of
layered networking models include the seven−layer
OSI model (which you need to know inside and out) and
the Department of Defense (DoD) five−layer model.
These two models are contrasted in Figure 3−1.
Figure 3−1: The seven−layer OSI model contrasts to
the five−layer DoD model.
Reasons why a layered−model
is used
Instant Answer Expect to see a question on the exam
that asks you to identify the reasons a layered model isused in
internetworking. Actually, there are myriad reasons why a layered model is
used, but we suggest thatyou memorize these possible responses:\
Change: When changes are made to one
layer, the impact on the other layers is minimized. If the
model consists of a single all−encompassing layer,
any change affects the entire model.
Design: A layered model defines each
layer separately. As long as the interconnections between
layers remain constant, protocol designers can
specialize in one area (layer) without worrying about
how any new implementations affect other layers.
Learning: The layered approach reduces a
very complex set of topics, activities, and actions into
several smaller interrelated groupings. This makes
learning and understanding the actions of each
layer and the model on the whole much easier.
Troubleshooting: The protocols, actions, and data
contained in each layer of the model relates only
to the purpose of that layer. This enables
troubleshooting efforts to be pinpointed on the layer that
carries out the suspected cause of the problem.
Standards: Probably the most important
reason for using a layered model is that it establishes a
prescribed guideline for interoperability between
the various vendors developing products that
perform different data communications tasks.
Remember, though, that layered models, including the
OSI model, provide only a guideline and framework,
not a rigid standard that manufacturers can use
when creating their products.
The layers of the OSI
model
Under its official name, the Open Systems
Interconnection Reference Model, the OSI model was developedby the ISO
(International Standards Organization) and released in 1984. Yes, it is the ISO
OSI.
The OSI model is a layered model that describes how
information moves from an application program
running on one networked computer to an application
program running on another networked computer. Inessence, the OSI model
prescribes the steps in the process of transferring data, in the form of ones
and zeroes,over a transmission medium to another computer or device on a
network.
Moving down through the layers
The OSI model breaks the network communications
process into seven separate layers. From the top, or thelayer closest to the
user, down, these layers are:Remember
Layer 7 _ Application: The Application layer provides
services to the software through which the
user requests network services. This layer is not
nor does it contain any applications, and your
computer application software is not on this layer.
In other words, a program like Microsoft Word or Corel does not exist at this
layer, but browsers, FTP clients, and mail clients do.
· Layer
6 _ Presentation: This
layer is concerned with data representation and code formatting.
Layer 5 _ Session: The Session layer establishes,
maintains, and manages the communication session
between computers.
Layer 4 _ Transport: The functions defined in this
layer provide for the reliable transmission of data
segments as well as the disassembly and assembly of
the data before and after transmission.
Layer 3 _ Network: This is the layer on which
routing takes place and, as a result, is perhaps the
most important OSI layer to study for the CCNA test.
The Network layer defines the processes used
to route data across the network and the structure
and use of logical addressing.
Layer 2 _ Data Link: As its name suggests, this layer
is concerned with the linkages and
mechanisms used to move data about the network,
including the topology, such as Ethernet or Token
Ring, and also deals with the ways in which data is
reliably transmitted.
Layer 1 _ Physical: The Physical layer_s name says it
all. This layer defines the electrical and
physical specifications for the networking media
that carry the data bits across a network.
PDU Names on the Layers of the OSI Model
OSI Layer PDU
Name
Application
PDU
Presentation
PDU
Session PDU
Transport
Segment
Network Packet
Data Link Frame
Physica l
Bits
OSI Reference Model
This model was established in 1970 by ISO. It is data
communication model.
It is logical and conceptual model.
This model has 7 layers:
1. Application Layer
2. Presentation Layer
3. Session Layer
4. Transport Layer
5. Network Layer
6. Data link Layer
7. Physical
Layer
1)
Application Layer
Deals with the communication of software on different
machines.
For example:
HTTP, FTP, SMTP, Telnet and DNS servers, all operating systems, web browsers,
communication software (messengers, Skype etc).
2)
Presentation Layer
Three
activities are taking place at this layer:
1) Encryption: The process of converting the plain text in to
cipher text for data confidentiality is called encryption. i.e. DES, 3DES and
AES
2) Translation: Coverts protocol from one form to other. Like
IPX to IP and vise versa.
3)
Compression: It simply works with the compression of data like win zip.
3) Session
Layer
A time period
in which two machines communicate is called a session.
This layer
deals with:
Session establishment: To establish a session before data
communication.
Session management: To manage the session throughout the
communication.
Session termination:
To manually terminate the session or there is a network down.
4)
Transport Layer
It uses protocols to transfer data from one machine to
another machine.
Two
protocols work on this layer, TCP/IP and UDP.
TCP/IP
(Transmission control protocol/Internet protocol)
It provides error recovery.
It relies on
IP for end-to-end delivery of data, including routing issues.
Functions
of TCP/IP
1. Multiplexing using port number
TCP identifies applications by their port numbers.
Multiplexing relies on the use of a concept called a socket
Socket consist of three things
1. IP address
2. Transport protocol (TCP or UDP)
3. Port number
Multiplexing helps in running multiple applications on a
machine. PC keeps every application separate and transfers data accordingly.
Every application and protocol has port number.
Port number identifies data that which application this
data belong to.
Like:
Telnet 23
SMTP 25
HTTP 80
HTTPS 443
DNS 53
Range of Port
number is 1 – 65536.
1 – 1024 are
already assigned.
2. Error
recovery
TCP numbers data bytes
using the sequence and acknowledgement fields in the tcp header
TCP sends data in
sequence
Sender also
sends re-transmission timer.
3. Flow
control using Windowing
TCP implements flow
control by taking advantage of sequence and acknowledgement fields in the TCP
header.
Window size is the
number of packets sent before getting acknowledgement.
It starts with smaller size of window than
gradually increases until some error occurs.
UDP (user
data gram protocol)
It is connection less
protocol.
It also works at
transport layer.
It does not do any
error recovery thus it takes less bandwidth.
It perform
§ Data transfer
§ Data segmentation
§ Multiplexing using port numbers
5)
Network Layer
It deals with the
function of path selection and logical addressing
The protocols use are:
§ IP (internet protocol) in TCP/IP
§ IPX in Novell
§ DDR in AppleTalk
Every network and host
has IP address.
IP define three
different network classes:
§ Class A 1-126
§ Class B 128-191
§ Class C 192-223
Router works on this layer
6) Data Link Layer
This layer is divided
into two sub-layers
§ LLC Sub-layer: it create link between
network and data link layer. For example ARP.
§ Mac Sub-layer: it deals with error
detection, addressing and orderly delivery of frames.
Addressing: In many
networks more than two devices are attached to the same physical network.
Data link layer
defines addresses to make sure that correct device listen and receive data.
In Ethernet data link
layer uses Media Access Control (MAC) address.
It is 48-bit long
address.
It also performs error
detection.
It put a field of FCS
(frame check sequence) in a frame. This field holds the value of CRC (cyclical
redundancy check) algorithm.
This CRC value is
calculated by mathematical formula applied on data in the frame.
Same value in
generated on destination, if values are same than there is no error.
It does not perform error recovery only error
detection
7) Physical layer
It is pure hardware
layer of OSI model.
On this layer frame is
converted into bits.
Hubs, repeaters and all cables work on this
layer.
Data on different layers
Data on Transport
layer is called a segment.
Data on Network layer
is called a packet.
Data on Data link
layer is called a frame.
Data on Physical layer is converted into bits.
Network Media
1. Guided
media: Wired network.
Examples are
coaxial, UTP, STP, Fiber optic cable
2. Un-guided
media: Wireless network.
Coaxial cable types
Thick net 500m.
Thin net 185m.
Maximum bandwidth in
coaxial cable is 10Mbps.
It is used in bus
topology.
EMI: electromagnetic interference occurs in
the cable when electron passes through.
UTP (Unshielded Twisted pair cable)
It has eight wires,
they are twisted with one another in a pair due to minimize of EMI, and their
wires have external coating.
Max distance
in UTP is 100m.
UTP categorization
CAT 1: use
only for voice
CAT 2: use
only for voice
CAT 3: support
data and voice
CAT 4: data
and voice, 4Mbps
CAT 5: data
and voice, 100Mbps
CAT 5E / 6:
1000Mbps or up to 1Gbps
Methods to make network with UTP cable
Straight
UTP method
Use to connect
different devices.
Cross UTP method:
Use to connect similar devices
STP (shielded twisted pair
cable)
It has extra insulation
It is use in special cases where EMI is more
as in factories.
Fiber optic cables
It support larger
distances.
It has no electro magnetic radiation.
There are two
categories of fiber optic cables
1. Multimode fiber (MM)
2. Single mode
fiber (SM)
Single mode fiber
LASER is used to
inject the light in this mode of fiber.
Data rate is up to
40Gbps on LAN and it may go to 100Gbps in future.
If we are using 10Gbps
in single mode fiber than distance is more than 1km.
It is expensive.
Multimode fiber
LED is used to inject
the light In multimode fiber.
Number of light rays
is passing through reflection process in this mode of fiber.
Data rate is up to 10Gbps in multimode fiber.
Distance is 500m
Network topologies
Star
topology
Each device is
connected to a central device which is a switch/hub.
Switch is commonly
used because it is an intelligent device as compare to hub. Also switch is a
configurable device. Through switch we can manage whole network.
Star topology is also
called hub and spoke topology
The PCs are connected
to the central device through a cable normally UTP but we may use fiber optic
etc.
This is the topology which is used nowadays.
Bus topology
Co-axial cable is used
to connect the devices. The data rate of this cable is 10Mbps.
There is a single
point of failure means if any one cable is broken then whole network would be
down.
It transmits the
electrical signal from one end of a cable to the other end of a cable
This topology
obsolete in early 90s.
§
10base2 network
uses a bus topology
§
10baseT using
hub network uses a bus topology
§ 10baseT using switch network
is a star topology
Ring topology
This topology is used by IBM machines to communicate between
them.
Each device is
connected directly to others so that the signal is repeated in one direction,
creating ring or loop.
There is a network
interface card used called token ring NIC.
An empty token is
passed from one PC to another in clockwise direction. if any PC wants to send
the data, it will grab the data, inject the data and then forward the token.
The cable used for communication is called
Shielded twisted pair (STP).
Disadvantages:
This topology is very
slow.
There is a single
point of failure.
There is no centralized management.
Full
Mesh topology
It means that all the respective nodes
in the network have a direct
