The OSI model is a useful tool in troubleshooting a network because it enables you to isolate a problem to a particular software module or piece of hardware. In this project, after reading the description of a problem, identify the OSI model layer or layers that are most likely involved

1) Layer 4, transport

2) Layer 2, datalink

3) Layer 5, session

4) Layer 7, application

Description of Problems are as below:

1) One of your servers has been exhibiting sluggish network performance. you use a network-monitoring program to try to evaluate the problem. You find considerable TCP retries occurring because the server is being overwhelmed by data, and packets are being discarded.

2) You check some statistics generated by a network-monitoring program and discovers that an abnormally high number of CRC errors were detected. (Hint think of the cause of CRC errors).

3) A user is trying to connect to another computer, but the logon attempt is continually rejected.

4) You try to access a Linux server to share files by using NFS. You can communicate with the server, but the shared files don't appear to be available.

Explanation:

OSI Model is a reference model to determine how applications communicate over a network. OSI consists of seven layers, and each layer performs a particular network function. The seven layers are:

Layer 7 - Application.

Layer 6 - Presentation.

Layer 5 - Session.

Layer 4 - Transport.

Layer 3 - Network.

Layer 2 - Data Link.

Layer 1 - Physical.

1) One of your servers has been exhibiting sluggish network performance. you use a network-monitoring program to try to evaluate the problem. You find considerable TCP retries occurring because the server is being overwhelmed by data, and packets are being discarded.

Layer 4, transport

2) You check some statistics generated by a network-monitoring program and discovers that an abnormally high number of CRC errors were detected. (Hint think of the cause of CRC errors).

Layer 2, Data Link

3) A user is trying to connect to another computer, but the logon attempt is continually rejected.

Layer 5, session

4) You try to access a Linux server to share files by using NFS. You can communicate with the server, but the shared files don't appear to be available.

Layer 7, application