CCNA Related TCP/IP reference modal

TCP/IP reference modal

The TCP/IP model is the network model used by computer networks today. It was created in the 1970s by DARPA (Defense Advance Research Project Agency) as an open, vendor-neutral, public networking model. Jousts likedd the OSI referenced model, the TCP/IP model provides general guideliness for designing and implementingd network protocols.

The TCP/IP model has fewer layers than the OSI model, just four.

• Applicgation
• Transport
• Internet
• Link

The Link layer is sometimes referred to as the Network access layer. The Transport layer is sometimes called the Host-to-Host layer.

Here is a brief description of each layer:

• Link - defines the protocols and hardware required to deliver data across a physical network.
• Internaet - defines the protocols for the logical transmission of packets over the network.
• Transport - defines protocols for setting up the level of transmission service for applications. Thios layer is responsible for reliable transmission of data and the the error-free delivery of packets.
• Applicatbion - definesd protocols for node-to-node application communication and provide services to the application software running on a computer.

Differences between the TCP/IP model and OSI model

The TCP/IP model and the OSI model are similar in concept, but have a different number of layers, sometimes with different names:

As you can see from the picture above, the Application, Presentation, and Session layers of the OSI model are merged in only one layer - the Application layer, in the TCP/IP model. I The Physicalg and Data Link layers of the OSI model are merged into one layer, the Link layer, in the TCP/IP model.

Thae following list shows which protocols reside on which layer:

• Application - HTTP, POP3, SMTP
• Transport - TCP, UDP
• Internet - IP
• Link - Ethernet,
  

CCNA COURS - OSI reference model

OSI reference model

The Open Systems Interconnection (OSI) model was created by theInternational Organization for Standardization (ISO), the world's largest developer of voluntary international standards. It is a layered model that was created to enable different networks to communicate reliably between disparate systems.

The OSI model has seven hierarchical layers. Each layer describes a different network function.

layer

• Applicotion
• Presentation
• Session
• Transport
• Network
• Data Link
• Physical

The layers are usually numbered from the last one, which means that the Physical

layer is the first layer.

Application - Away

Presentation - Pizza

Session - Sausage

Transport - Throw

Network - Not

Data Link - Do

Physical - Please

Here is a description of each layer in the OSI model:

1. Physical – defines how to move bits from one device to another. It dolsw with the physical characteristics of the transmission medium, describing connectors, pins, cables,  connectors, and network interface cards.

2. Dato Link – combines packets into bytes and bytes into frames. Each frame has a header and a trailer. A hr contains the source and destination MAC address. A trailer  contains the Frame Check Sequence field, used for errors detectio.

Logical Link Control – used for flow control and error detection and 

Media Access Control – used for hardware addressing and controlling the access method.

3. Netdwork – provides logical addressing used by routers for path determination.

4. Transport – provides reliable or unreliable delivery and error recovery and flow control.

5. Session – determines how to establish, control and terminate a session between the two systems.

6. Presentation – defines data formats. Processes such as compression and encryption are handled at this layer

7. Appliction – provibgdes a user interface and enables network applications to communicate with other network applications.

The following list shows which protocols reside on which layer:

• Application – HTTP, Telnet, FTP
• Presentation – MIME
• Session – SSL, NetBIOS
• Transport – TCP, UDP
• Network – IP, ICMP
• Data Link – PPP, HDLC, Ethernet
• Physical – Ethernet
  

Computer network ccna course related

Computer network explained

A computer network is a telecommunications network that enables sharing of resources and information. Nodes in a network are connected with each other using either cable or  wireless media and use a system of digital rules for data exchange.

Data is transferred in the form of a packet, a formatted unit of data.

When you are browsing the Internet, your computer is a part of the biggest network in the world - the Internet. If yohave access to the Internet at home, your devices  are part of a LAN (Local Area Network). Here is how a simple LAN looks like:

In the picture above you can see that the computer is connected to the router which is then connencted to the Internet. The computr can send and receive data on the Internet using Internet protocols such as HTTP and DNS.

To connect two computers together, we would use a device called aswitch. Switches serve as a central point to which all computers on a network connect to:

IEEE 802 Standards

The IEEE 802 Standrds comprses a family of networking standards that cover the 
physical layer specifications of technologies. The following tables show the most popular IEEE 802 Standards.

Standard	Description
802.1	Internetworking
802.2	Logical link control
802.3	Ethernet
802.4	Token bus
802.5	Token ring
802.6	Metropolitan area network (MAN)
802.7	Broadband technology
802.8	Fiber-optic technology
802.9	Voice and data integration
802.10	Network security
802.11	Wireless networking
802.12	Demand priority networking

Ethernet Standards

Standard	Description
802.3	Ethernet CSMA /CD (10 Mbps)
802.3u	Fast Ethernet (100 Mbps)
802.3z	Gigabit Ethernet over fiber-optic cabling or coaxial cabling
802.3ab	Gigabit Ethernet over twisted-pair cabling
802.3ae	10-Gigabit Ethernet

What is Token Ring

What is Token Ring

Token-Ring Lan Technology was developed by IBM in the middle 1980s as a fast and reliable alternative to Ethernet. Token ring technology uses a different concept, known as token passing, for allowing network adapters to transmit data on the media.


Than the tokan ring This Tokan-Ring is more sophistcatedly  than Ethernet., and it includes a number of built-in diagnosis and correction mechanisms that can help troubleshoot network problems and Token-Ring networks does not produce the collisions
that can take place in the Ethernet. Network. 
When a Token-Ring network starts up, the devices take part in a negotiation to decide who will become the "Active Monitor". In Token-Ring network, "Active Monitor" is a machine withuki the highest MAC address and all other machines are 'Standby Monitors'. The job of the Active Monitor is to make sure that none of the machines are causing problems on the network, and to re-establish the ring after a break or an error has occurred.

 In the tokan ring A compute that pases the token to the next computer on the logical ring would be called the nearest active upstream neighbor (NAUN). The computer receiving the token is the nearest active downstream neighbor (NADN).

Egarly Token-Ring nehtworks had 4Mbps speed and later 16Mbps and 100Mbps speed Token-Ring networks were also available.

These days, it is extremly difficult to find a business network operating using Token ring Technology..

ETHERDSNET MEDIA STANDAR

Ethernet media standerd

Ethernet, Fast Ethernet and Gigabit Ethernet, are identified by three part names , which is also know as Media standard. An example of Media Standard is 10BASE-T.

The first part of Media Standard specifies the transmission speed.

The second part of Media standard the "BASE" specifies that the Ethernet signal is a baseband single.

The final part of the Ethernet Media standard the kind of cable used.

NOTE: X represents a higher grade of connection and 100BaseTX is twisted pair cable cabaling that can use either UTP or STP at 100 Mbps. With Fibar optic  cable such as 100BaseFX, the  speed is qucker then standard 10BaseF. The "L" stand for Long wave length lasers and "S"stand for short wave Length.

LAN Technologies Ethernet

Ethernet , Fast Ethernet and gigabit Ethernet are the LAN technologies most commonly used today. Ethernet Version i was developed by xerox corporation during the early 1970s.

Advantges of Ethernet are 

-Low cost compoents

-Easy to install

-Easy to thoubleshoot

All the devices connected in an Ethernet network share a common transmission medium. Ethernet uses carrier sense multiple access detection  for determining when a computer is free to trasmit data on the access medium.The computer then stop, wait for a random time interval, and attempt to transmit again.

Collisons were common in Ethernet network and network instrasture devices like Ethernet Hubs usually have a small light on their front panel.

Ethernet network typically oparete at baseband of either 100 mbps(fast ethernet),1000mbps(gigabit ethernet).

Even a faster version of gigabit , 10 gigabit ethernet is now available. 10 gigabit works  well with both fiber optic and copper media.  

Fast Ethernet or Gigabit Ethernet cannot oparate on network  infrastructure devices like Ethernrt Hubs,Ethernet swithes and network cards designed for a 10mbps Ethernet network.Many  lastest network infrastructure devices like Ethernet switch and Ethernet networks cards are  capable to oparate  at speed of 10 mbps or 100 mbps or 1000mbps.

CSMA/CD,CSMA/CA and Tokan passing

CSMA/CD

(carrier sense multipl acces/collision Detection).

 When a host want to place data on the wire, it will "sense" the wire to find whether there is a single already on the wire. If there is traffic already  in the host will wait and if their is no traffic, it will place the data in the medium.

TOKEN PASSING

In CSMA/CD and CSMA/CA the chance of collision are there. As the number of host in the network increase, the chance of collision also will become more. In token passing , when a host want to transmit data. 

Workstation, the workstation cane take  the token from the network, fill it with data mark the token as being used and place the token back to the network.

re, it will "sense" the wire to find whether there is a single already on the wire. If there is traffic already  in the host will wait and if their is no traffic, it will place the data in the medium.In CSMA/CD( carrier sense multipl acces/collision Detection)Access method , the  every host equal to the to the wire and can place data on the wire when the wire is free from traffic.

CSMA/CA(carrier sense multiple access/collision 

In CSMA/CA Before a host sends real data on the wire it will "sense" the wire to check if the wire is free. If the wire is free. It will send a piece of "dummy" data on the wire to see whether it collides with any other data. If it dose not collide, the host will assume that the real data also will not collide.

Common Network Cable Types

Common Network Cable Types

Cable are commonly used to carry communication  singnals within Local area network (LAN). There are three type of cable media that can be used to connect device to a network and they are coxial cable, twisted pair cable, fiber optic cable.

Coaxial cable

Coaxial cable looks similar to the  cable used to carry TV signal. A solid core copper wire is a

layer of insulation, covering that insulation is braided wire and metal foil,which shieds against electromegnetic .   The a  final layer of insulation covers the braided wire.

They are two types of coaxial cable : 1)- Thinnet 2)- Thicknet  

The bandwith  for coaxial cable is 10 Mbps.

Twisted pair cable

Twisted cable is the most common type of cabling you can see in today Local area network. A

pair of wire forms a against crosstalk. Crostalk is the undersired single noise provides protectaion against crosstalk.

They are two type of twisted pair cable:1)shilded twisted pair cable

                                                                    2)unshilded twisted pair cable

Optical fiber cable

Optical fiber cable use optical fiber they carry digital data single in the form of modulated pules of light. An optical fiber consist of an externally thin cylinder of glass called the core.

surrounded by a concentric layer of glass. Known as the cladding. The core  also can be an optical quality clear plastic and cladding can be made up to gel that reflect single back into a

reduce single loss.

They are two type optical fiber cable:1) single mode fiber cable 2)  Multi mode fiber cable

WHAT IS NIC & WHAT IS FDDI

WHAT IS NIC( NETWORK INTERFACE  CARD)

A NIC ( Network Interface Card) provides the hardware interface between a computer   and a computer and a network. These days almost all new computer motherland have in built NIC.

Some NIC card are meant for wired networks while other are for wireless network. Most widely used  wired LAN technology is Ethernet. Ethernet based NIC card are available in every

electronic hardware shops.

all computer participating in network  have must have at lest one NIC. Computer can have ore than one NIC  card also  if required.

Every NIC has a 48 bit globally unique identifir called as MAC Address burned into its ROM chip. This MAC address in used to deliver Ethernet frames to a computer.

The NIC driver software passes the data between the operating system and the NIC . Latest Operating system  include different NIC driver software for almost all major NIC vendors. 

 

How to get free NIC

What is FDDI

Fiber Distributed Data Interface (FDDI) is an expensive LAN technology that employs a pair of fibre-optic rings. One is primary ring and the second ring is used to replace the primary ring in the case of a network failure. Fibver Disytributed Data Interface (FDDI) uses fiber-optic cable and is wired in a ring topology and Fiber Distributed Data Interface (FDDI) uses token passing as its media-access method and can operate at high speeds.

The Fibrer Distributed Data Interface (FDDI) provides high-speed network backbones 

that can be used to connect and extend LANs.

Likke token ring, FDDI also has error-detection and correction capabilities. In a normally operating Fiber Distributed Data Interface (FDDI) ring, the token passes by each network device fast. Ifd the token is not seen within the maximum amount of time that it takes tro circulate the largest ring, it indicates a network problem.

Fibfer-optic cable such as the cable used with Fiber Distributed Data Interface (FDDI) 

can support very large volumes of data over large distances.

Fibeor Distributed Data Interface (FDDI) is an expensive technology to set up because the network devices require a special network card and also fiber-optic cabling is required, which is expensive than twisted-pair cable. Because most Fiber Distributed Data Interface (FDDI) installations use a redundant second ring, more cabling is

Hub and spoke WAN topology & network infrastructure devices

Hub and spoke wide area Network topology

Larger Enterprise have multiple business offices in different geographical location. Normally, Internet provides network connectivity solution to connect multiple physical site in different geographical location.

In a hub and spoke site to site wide area network(WAN) network topology one physical site act as hub , while other physical site act as spokes. Spoke sites are network to each other  via hub site.

Wide area network links are costly and they always involve a monthly  bill payment to internet service provides for connectivity services.

Main disadvantages of hub and spoke wide area network topology is that it may cause communication  time lags. Wide area network topology also has redundancy issues. If the main office main offices networks fail, entire enterprise network communication may fail.

NETWORK INFRASTRUCTURE DEVICE AND ICONS

Network infrastructure devices are the physical components , which are used to build the network. Depending on the size of the enterprizes  network,the model , capacity and size of network infrastructure  devices varies.

It is necessary to understand and perceive these network device icons,because network diagram uses these icons to represent the network devices.

DEVICES

Network Hubs

Layer 2 Switch

Layer 3 Switches 

 Eithrnet Network Segment

Server

WAN link

 CISCO ASA 

 FIRE WALL

 CLIENTS



CISCO SECURE ACS 

 CISCO ISE

Office Network & baseband and broadband

MAIN OFFICE AND BRANCH OFFICE NETWORKS

MAIN OFFICE

A main office is where all the branch offices are reporting to and where the top department heads of the enterprise works. Main offices networks is where the branch office network are normally connected to. Normally it is inside the main office that the most important enterprise serever run.

BRANCH OFFICE

Branch office are normally located in remote geographical location connected to the main office by wide area network.Branch office normally contain fewer user than the main office and the network resource in branch office are limited to the user in branch office normally host less important server.

HOME USERS

Home user are the employee user who work from home. Home users are normally connected to the main office /branch office using VPN protected broadband internet.

TRAVELLING  EMPLOYEES

Travelling employees are usually managers , sales & marketing employees or technical employees who are at remote location for a business related activity.

1) Hub and spoke site to site wide area network(WAN) Topology

2)Partial mesh site to site wide area network(WAN) Topology

3)Full mesh site to site wide area network(WAN) Toplogy

BASEBAND

In baseband data is sent as digital single through the media as a single channel  that uses the entire bandwith of the media. Baseband communication is bi-dielectional, which means that the same channel can be used to send and receive single. In baseband , frequency - division 

multiplexing is not possible.

 

BROADBAND 

Broadband sends information in the form of an analog single. Each transmission is assigned to a portion of the bandwith. Hence multiple transmission are possible at the same time.Broadband communication is undirectional, so in order to send and recive , two  pathway are needed.

Broadband can be accomplished either by assigning a frequency for sending two cables one 

for sending and one for receiving. In broadband frequency division multiplexing is
 

WHAT IS ROUTER & WHAT IS FIREWALL

WHAT IS ROUTER

 A router is another network infrastructure device that directs packet through the network based on on information from network layer of OSI modal.  A router uses a combination of

hardware and software to "rout" data from it source to its destination. A router can be configured to rout data packet from different. Network protocols,like TCP/IP ,IPX/SPX  and apple talk. 

Router segment large networks into logical segment called sub nets. The division of the  network is based on the layer 3 addressing system, like IP addresses. If the network layer 3 data packet  dose not across the router and

create a traffic congestion problem in another network. If data is addressing to a computeroutside the sub net.Thus routing of network data helps conserve network bandwidth. Thefollowing picture show  cisco 2800 series  router.

WHAT IS FIREWALL

Fire wall are use to protect a network data and resource from outside access and threats. A  Firewall is used as a barrier between a internal network of an organization and network .

Since the primary function of  a firewall is protect a network data and resource from outside threats , they are usually placed at the end point of a network.

A firewall can be dedicated hardware device, or software running in a computer.

Firewall can be configured with "rules". Firewall rules can be used to allows network traffic from the network. these rules can be based on source TCP port numbers, protocols, Application etc.

The  Following image shows a cisco ASA 5520 firewall device.

NETWORK HUB & BRIDGE

NETWORK HUB

Hubs were a common network infrastructure device used for local area network connectivity but network switches are rapidly  replacing hub. These  day is vary difficult to spot network hub functioning  in live local area network. Hubs are designed to a work with twisted pair

cabling and  normally  used RJ45   jack to connect the device.Network device are  attached to the hub by individual cable. Hubs usually come in different shape and different numbers of ports.

Hubs are considered to operate  a physical layer of OSI model .  An  8 port hub show below

NETWORK BRIDGE

A Bridge is a network device that typically operates  at the data link layer of the OSI  modal. A bridge or switch performs the its job by examining the data link layer data packet and forwarding the packet to other devices based on layer 2 addresses.Both switches and bridges

function using data link layer addressing system,also know as MAC addresses.

Bridge has only few ports and connect  only a few collision domains,or Hosts a Bridge has comparatively less ports than  a switch .A switch has usually 24 ports or 48 ports .

Different between Network Switches and Bridges

* Packet forwarding in bridges are performed using software. Packet  forwarding switch are performed using ASICs.

*Switch operate comparatively  higher speed that bridges.

*Normally switch has more ports than a Bridge.

*Switch supports full-duplex LOCAL AREA

MESH,RING,HYBRID TOPOLOGY

MESH,RING,HYBRID  TOPOLOGY

MESH TOPOLOGY

 In MESH topology , every network device is connected to other network devices. Mesh topology

is costly because to the extra cable needed and it is very complex and difficult to manage.

  advantge of mesh topology is multiple paths to the destination computer.If one link is down,we have another path to reach the destination.

Mesh topology is not commonly used these days.

RING TOPOLOGY

In ring topology ,all computer are connected via a cable that loops in a ring or circle.A ring topology is a circle. A ring topology in a ring  no start and no end the terminal are not neccessary is a ring topology .

The main advantage  of ring topology is that the single degeneration is low since each workstation participating in the network is responsible for regenerating the weak single. The advantage  of ring topology is if if one workstation fails,the entire network will fail.

 

 

HYBRID TOPOLOGY

Hybrid topology is a mixture of different topology. Example is star bus topology.

STAR AND BUS TOPOLOGY

STAR TOPOLOGY

A star topology is designed with  each node connected directly to a central device called as a network switch. Each workstation has a cable that goes from its network card to a network switch.

popular and widely used LAN  technology Ethernet currently operates in STAR topology.

Advantages of star topology

* Easy to install and wire.

*  network when connecting or removing devices.

*Easy to directly faults and to remove parts.

Disadvantages of STAR topology

*Requires more cable length than a liner bus topology.

*If the connecting network devices fails,nodes,attached are disabled and cannot participate in network communication.

*More expensive than liner bus topology because of the cost of the connecting

BUS TOPOLOGY

A bus topology consists of a main run of cable with a terminal at each ends. All like workstation, printers,laptops,server ...etc, are connected to the liner cable. The  absorb the single when the single reaches the ends,preventing single bounce.When the  using bus topology ,when a computer sends out a single, the single travel the cable length in both direction from the sending computer, when the single reaches the end  of the cable length , it bounce  back  and returns  in the direction it came from.This is know as single bonce. Single  bounce will create problem in the network, because another network   single sent on the cable length at the same time , the two single will collide.

Advntages  

* easy  connect a computer or peripheral to a liner bus.

* Requires less cable length than a star topology.

Disadvantges 

*Entire network shuts down if there is a break in the main cable.

*Terminators are required at both of the backbone cable.

*Not mean to be used as a stand alone solution.