Question

1. List ALL the different type of network connections involved in the operations for each of the scenarios below. Provide an illustration for each of the scenarios.

Scenarios a. You have just bought a new mobile phone from an online shop. You have decided to take a few snapshots of your best friend and send them to the email account of a mutual friend across the country. b. You are driving around in an unfamiliar city and have just gotten lost. By using your mobile phone’s GPS system, you submit a request for driving directions from a nearby intersection to your destination.

2. Broadcast networks refer to networks such as LANs connected by a technology such as Ethernet. Broadcast networks, by nature, are multiaccess where all routers in a broadcast network can receive a single transmitted packet. Discuss the requirements or deficiencies of a network layer (OSI layer 3 and TCP/IP layer 2) in a broadcast network.

Answer 1

1.Scenarios a.

To send the snapshots via email,the user may do that through INTERNET.The Email will be sent through a protocol called SIMPLE MAIL TRANSFER PROTOCOL(SMTP).

The internet connectivity may be of the following types:

• BROADBAND :The most common used term these days and is very fast.The connection may be wired or wireless.But in this case as it is a mobile,WIRELESS connectivity is provided through WIFI receiver if that mobile.
• MOBILE NETWORK:: This is also a frequently used network now-a-days.As a mobile will have a SIM card, it can get connected to the world of INTERNET through MOBILE NETWORK.It's spped depends on the signal the mobile receives.

b.

Global Positioning System (GPS) is a worldwide radio-navigation system formed from the constellation of 24 satellites and their ground stations. The Global Positioning System is mainly funded and controlled by the U.S Department of Defense (DOD). The system was initially designed for the operation of U. S. military. But today, there are also many civil users of GPS across the whole world. The civil users are allowed to use the Standard Positioning Service without any kind of charge or restrictions.

GPS works with having mobile Network and also broadband.But, we cannot be always STAY connected to either of those networks.,then there a question arises that

CAN I USE GPS WITHOUT INTERNET CONNECTION?

Absolutely YES. we can use GPS even we lose the connection.

GPS system in your mobile can work in two ways:

When you have a data connection, your phone uses Assisted GPS, or A-GPS. This uses the locations of cell phone towers and known Wi-Fi networks to figure out roughly where you are. When you first load your navigation app, you’ve probably seen your location go from a big blue circle to a smaller, more precise circle.

That big circle comes from the cell tower and crowd-sourced Wi-Fi information, while the smaller, more precise circle comes once the information from GPS satellites gets added to the mix.

A-GPS doesn’t work without data service, but the GPS radio can still get a fix directly from the satellites if it needs to.

Finding the initial location will take longer with this method, and the accuracy will be more dependant on things outside of your control like terrain and surrounding buildings, but it does work.

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2.

Network layer manages options pertaining to host and network addressing, managing sub-networks, and internetworking.

Network layer takes the responsibility for routing packets from source to destination within or outside a subnet. Two different subnet may have different addressing schemes or non-compatible addressing types. Same with protocols, two different subnet may be operating on different protocols which are not compatible with each other. Network layer has the responsibility to route the packets from source to destination, mapping different addressing schemes and protocols.

Functionalities

Devices which work on Network Layer mainly focus on routing. Routing may include various tasks aimed to achieve a single goal. These can be:

• Addressing devices and networks.

• Populating routing tables or static routes.

• Queuing incoming and outgoing data and then forwarding them according to quality of service constraints set for those packets.

• Internetworking between two different subnets.

• Delivering packets to destination with best efforts.

• Provides connection oriented and connection less mechanism.

Network Layer Features

With its standard functionalities, Layer 3 can provide various features as:

• Quality of service management

• Load balancing and link management

• Security

• Interrelation of different protocols and subnets with different schema.

• Different logical network design over the physical network design.

• L3 VPN and tunnels can be used to provide end to end dedicated connectivity.

Internet protocol is widely respected and deployed Network Layer protocol which helps to communicate end to end devices over the internet. It comes in two flavors. IPv4 which has ruled the world for decades but now is running out of address space. IPv6 is created to replace IPv4 and hopefully mitigates limitations of IPv4 too.

Design Issues with Network Layer

• A key design issue is determining how packets are routed from source to destination. Routes can be based on static tables that are wired into the network and rarely changed. They can also be highly dynamic, being determined anew for each packet, to reflect the current network load.
• If too many packets are present in the subnet at the same time, they will get into one another's way, forming bottlenecks. The control of such congestion also belongs to the network layer.
• Moreover, the quality of service provided(delay, transmit time, jitter, etc) is also a network layer issue.
• When a packet has to travel from one network to another to get to its destination, many problems can arise such as:
  • The addressing used by the second network may be different from the first one.
  • The second one may not accept the packet at all because it is too large.
  • The protocols may differ, and so on.
• It is up to the network layer to overcome all these problems to allow heterogeneous networks to be interconnected.