The OSI Model and TCP I Discussion

Question #1: Compare and contrast two layers of the Open Systems Interconnection (OSI) reference model, including the protocols that run each layer.

The OSI model is split into seven different layers with the top three layers will be defined by how the applications with the end stations will communicate with each other and the users. The bottom four layers will be defined by how data is transmitted end to end. The application layer is where the end user will communicate with the computer and the application layer will determine the availability of communicating partners along all the resources being necessary to make the connection. The application layer is also responsible for identifying and establishing the availability of the intended communicator partner and determining whether sufficient resources for the intended communication exist. While the application layer is on the very top of the OSI layers, the physical layer is on the bottom and this layer is responsible for two very important steps, it sends and receives bits. This layer communicates with the communication media and specifies the functional requirements for activating and maintaining the physical link between the end systems.

Question #2: What was the reason that IPv6 was introduced? Why do you think many organizations are not upgrading their network, soley to IPv6 and run that protocol instead of running IPv4?

IPv6 was specifically designed to solve address space exhaustion and was seen all the way back to the 1980’s of having limited scalability and capability. While IPv6 does offer better capabilities, security and expansion, it is also more complex. IPv4 uses a 32-Bit address and IPv6 uses 128-Bit hexadecimal address. The biggest reason that this has not been taken up comes down to money and resources and being able to transfer an entire network over with minimal downtime. With the increase of internet availability around the world expanding and the growth of the world, most places will only upgrade when and if it is necessary to continue business without having much choice.

Question #3: What is the purpose of subnetting when using IPv4 addressing? What role does subnet mask play in a subnetting of IPv4?

The purpose of subnetting IPv4 addressing is it allows variations of the network and host segments of the single network address. With the known issue of IPv4 having address space exhaustion as far back is the 1980’s, it allows the configuration of internal networks into different subnets and allows an enhancement of local routing capabilities.  The role of subnet masks play with IPv4 is it allows an IP to be divided into two parts. One portion will identify the host computer and the other will identify the network for which it belongs.