Networking and Telecommunication: The Network Layers

a. What does the network layer do? What is interior routing and what is exterior routing?

In the Open Systems interconnection Model (OSI Model), the network layer lies in the third level and for network communication it provides paths for data routing. It is considered as the backbone of the OSI model because for the purpose for the data transfer between nodes, network layer performs selection and management of the best logical path. Switches, firewalls, bridges and routers are some hardware devices that this layer contains. From the transport layer it responds to requests and issues requests to the data link layer.

The process of moving data from one network to another is known as routing.

Interior Gateway Protocols (IGPs) handle routing within a single Autonomous System. They keep track of paths which are used to move data from one system to another inside a network. All the networks communicate with each other through IGPs.

On the internet if we need to get from one place to another outside a network, the use of Exterior Gateway Protocol (EGP) come into play or for the purpose of communication between multiple autonomous system we use EGP.

b. What is quality of service routing and why is it useful?

The set standards and mechanisms for enabling high quality performance for applications are known as quality of service routing. Its main goal is to provide special service for applications that need it by making sure the required bandwidth is provided, controlling latency and making sure the loss of data is reduced. Some of its useful features are:

 User experience is improved.

 Uses the resources that already exist and reduces cost which reduces the need for upgrades and growth.

 Administrators are allowed control over networ...

... middle of paper ...

...tiple IP addresses and VLANs because of its connection with different VLANs and three subnets. Up receiving the message, the router being layer 3 device strips off the Ethernet frame and reads the IP packet. The router looks into the routing table and notices that the destination IP address (179.58.10.101) is within a subnet it controls ( 179.58.10.1). The new Ethernet frame is now created by the router and sets the destination Ethernet address to the destination computer2. If makes the use of ARP if it is necessary and sends the frame to switch 3. Switch 3 reads the Ethernet address and looks it up in its forwarding table. It finds out that the frame needs to go to Switch 1. The VLAN tag field is now set and forwards the frame over the trunk to Switch1. Switch 1 removes the VLAN tag information and sends the frame to the correct computer (Computer2). In our case