Question

Discuss how you would envision the different layers defined in the OSI Reference Model to interact.

• Provide an example of how you would use the OSI model when troubleshooting a network connectivity problem

Answer 1

OSI REFERENCE MODEL:

The model uses layers to assist provides a visual description of what's occurring with a specific networking system. this could facilitate network managers slender down issues , similarly as laptop programmers. school vendors mercantilism new product can usually see the OSI model to assist customers perceive that layer their product work with or whether or not it works “across the stack”.

When most non-technical folks hear the term “seven layers”, they either think about the favored Super Bowl dip or they erroneously have confidence the seven layers of Hell, courtesy of Dante’s Inferno (there are nine). The seven layers see the Open Systems Interconnection (OSI) model, a abstract framework that describes the functions of a networking or telecommunication equipment.

Layer seven - Application:

To any our dip analogy, the appliance Layer is that the one at the highest - it’s what most users see. within the OSI model, this can be the layer that's the “closest to the tip user”. Applications that job at Layer seven are those that users move with directly. an online browser (Google Chrome, Firefox, Safari, etc.) or different app - Skype, Outlook, workplace - are samples of Layer seven applications.

Layer six - Presentation:

The Presentation Layer represents the world that's freelance of information illustration at the appliance layer - generally, it represents the preparation or translation of application format to network format, or from network information to application format. In different words, the layer “presents” information for the appliance or the network. a decent example of this can be secret writing and coding of information for secure transmission - this happens at Layer six.

Layer five - Session:

When 2 devices, computers or servers ought to “speak” with each other, a session must be created, and this can be done at the Session Layer. Functions at this layer involve setup, coordination (how long ought to a system look forward to a response, as an example) and termination between the applications at every finish of the session.

Layer four – Transport

Transport layer is to blame for reliable delivery of information from one finish to a different. It makes positive that a receiver receives the complete information intact. Transport layers have many protocols making certain reliable information transfers. protocol and UDP ar the 2 most generally used protocols. Firewalls are the ordinarily used networking devices within the transport layer.

Layer three - Network

Here at the Network Layer is wherever you’ll realize most of the router practicality that almost all networking professionals care concerning and love. In its most simple sense, this layer is to blame for packet forwarding, together with routing through totally different routers. you may grasp that your capital of Massachusetts laptop needs to attach to a server in American state, however there ar ample totally different ways to require. Routers at this layer facilitate try this with efficiency.

Layer two– Data Link layer

The Data Link Layer provides node-to-node information transfer (between 2 directly connected nodes), and additionally handles error correction from the physical layer. 2 sub layers exist here similarly - the Media Access management (MAC) layer and also the Logical Link management (LLC) layer. within the networking world, most switches operate at Layer a pair of.

Layer one - Physical

At rock bottom of our OSI dip we've got the Physical Layer, that represents the electrical and physical illustration of the system. this could embody everything from the cable kind, oftenness link, similarly because the layout of pins, voltages and different physical necessities. once a networking drawback happens, several networking professionals go right to the physical layer to visualize that each one of the cables ar properly connected which the facility plug hasn’t been force from the router, switch or laptop, for example.

Network troubleshooting victimization the OSI model:
The first step a user must absorb troubleshooting a network within the physical layer is to visualize whether or not all the physical parts concerned within the network are obstructed in and dealing properly. Most of the network problems occur owing to broken cabling or terminations. within the case of a wireless network, excessive signal attenuation and wireless interference are many common problems to look at out for. If of these aspects are verified and also the drawback still persists, you’ll ought to be to the data-link layer.

At the data-link layer, verify all the switch and VLAN configurations beside the mac addressing. If the matter still continues, search for information science address conflicts and take a look at to eliminate any duplicate information science addresses. As a final step, check the spanning tree protocol (STP), because it plays an important role in managing network loops, which frequently jam or flood the network.

Moving up to the network layer, you’ll realize that network addressing problems and routing problems are the foremost common issues that occur here. By confirmative all the routing protocols and information science addressing schemes used, trailing down the network issue is terribly straightforward. many potential causes for network problems are broken networking devices, incorrect device configurations, network information measure, and authentication problems. “Ping” may be a terribly handy and effective troubleshooting command to find network problems during this layer. A undefeated ping past the default entree means the net is functioning properly. “Trace,” “netstart,” “route,” and “netguard” commands are many different troubleshooting commands which will be employed in the network layer.

Most problems at the transport level revolve around ports that are blocked or broken. check that that there are not any firewalls obstruction the TCP/UDP ports. Finally, disabling quality of service (QoS) will generally resolve many network-related problems.

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