The connectivity issues between the end user and the DB Unit 2 can be understood with the help
Of OSI model reference. First a small description about OSI model.
Layers of OSI model:
1. Application Layer: Acts as an interface between the user and the software itself.
2. Presentation Layer: It is responsible for data representation, encryption and decryption.
3. Session Layer: Starts, maintains and terminates all new or ongoing sessions.
4. Transport Layer: This layer ensures reliability and flow control, either by TCP or UDP.
5. Network Layer: Provides the best path or selects the route between the source and the
6. Data Link Layer: It is responsible for transferring data between network entities and also
Corrects errors that may occur in the physical layer.
7. Physical Layer: Frames are converted into bits, 0 and 1 so that it can be easily transmitted as
Electrical impulses through wires.
Now, to troubleshoot connectivity issues between the PC and the DB unit we need to concentrate
Upon the last three layers, that is Network, Data Link and Physical.
We will have to go through the below mentioned points to check the connectivity.
Step 1: Physical Layer: Check all the physical connections provided through Ethernet cables like
Connection between PC and the DB unit. If at all a layer 2, that is switch is there in between the
Two we need to check all the ports whether up or not.
Step2: Data Link Layer: If there is a switch in between then we need to check whether the PC
And the server is on same VLAN or not. If not we need put them under same Van with
Identical IP addressing structure.
Step3: Network Layer: If the I addressing structure of the PC as well as the DB unit are not
Same, that is on different subnets we first need to check for a layer 3 device like a router which
Will route packets within two different networks.
Moreover, from the server side, we need to check all the services running up and fine.
After completion of all this activity there are utilities that can be tried from the PC to check
Connectivity between the two.
- Trace route.
Any one of these can be used to check the connectivity. The format of these commands is:
Ping x.x.x.x (x.x.x.x is the IP address)
Trace route x.x.x.x (x.x.x.x is the IP address).