The blog includes a vivid coverage of the concepts of CCNA, CCNP (Routing & Switching) , Basic Linux and Linux servers. Projects have also been simulated to give a practical exposure.

Monday, 11 February 2013

OSI Model Part 1

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CCNA (640-802)
CISCO CERTIFIED NETWORK ASSOCIATE
(R & S)

The CCNA certification was the first course and exam in the cisco certification process, and the precursor to all current Cisco certifications.

Test Cost for CCNA (Reviewed in 2013) is $295(16225INR).

SKILLS TO BECOME A CCNA :

  • Install, configure, and operate LAN, WAN, and wireless access services securely as well as troubleshoot and configure small two medium networks (500 nodes or fewer) for performance.
  • Use the protocols IP, IPv6, EIGRP, RIP, RIPv2, and OSPF as well as understand serial connections, frame relay, VPN, cables, DSL, PPPoE, LAN SWITCHING, VLANs, VTP, STP, Ethernet, Security and ACL.




DIFFERENT MODELS USED IN NETWORKING ARE:

OSI (7 Layered Model)
OPEN SYSTEMS INTERCONNECTION

When networks first came into being, computers could typically communicate only with computers from the same manufacturer. In the late 1970s, the Open Systems Interconnection (OSI) reference model was created by the International Organization for Standardization (ISO) to break this barrier. The OSI model was meant to help vendors create interoperable network devices and software in the form of protocols so that different vendor networks could work with each other. A reference model is a conceptual blueprint of how communications should take place. It addresses all the processes required for effective communication and divides these processes into logical groupings called layers.

Advantages of OSI layered Model:

  • It divides the network communication process into smaller and simpler components, thus aiding component development, design, and troubleshooting.
  • It allows multiple-vendor development through standardization of network components.
  • It allows various types of network hardware and software to communicate.
It prevents changes in one layer from affecting other layers, so it does not hamper development.

NOTE : Shortcut to remember layers of OSI Model from-
Layer 7-1 : All People Seen To Need Data Processing
Layer 1-7 : Please Do Not Through Sauces Pizza Away


OSI 7 layers :


Application layer (Layer 7)

  • The Application layer of the OSI model marks the spot where users actually communicate to the computer.
  • The Application layer is also responsible for identifying and establishing the availability of the intended communication partner and determining whether sufficient resources for the intended communication exist. Applications sometimes require more than only desktop resources. Often, they’ll unite communicating components from more than one network application. Prime examples are file transfers and email, as well as enabling remote access, network management activities, client/server processes, and information location.



Presentation layer (Layer 6)
  • It presents data to the Application layer and is responsible for data translation and code formatting.
  • The OSI has protocol standards that define how standard data should be formatted. Tasks like data compression, decompression, encryption, and decryption are associated with this layer. Some Presentation layer standards are involved in multimedia operations too.

Session Layer (Layer 5)
  • The Session layer is responsible for setting up, managing, and then tearing down sessions between Presentation layer entities.
  • This layer also provides dialog control between devices, or nodes.
  • It coordinates communication between systems and serves to organize their communication by offering three different modes: simplex, half duplex, and full duplex. To sum up, the Session layer basically keeps different applications’ data separate from other applications data.



Made By : P & V        
                                                   
                                               Continue :- OSI MODEL Part 2

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