Important points for chapter 5

At the transport layer, TCP and UDP ensure reliable or unreliable end to end communications and directing the traffic to the correct application using port numbers

At the network layer, IP ensure that both source and destination are identified by IP addresses

The segment (TCP + Data or UDP + Data) is encapsulated by the IP header to form a packet.

At the network layer, there are various protocols IPv4, IPv6, Appletalk and IPx. For this module we focus on IPv4.

IPv4 is connectionless (does not establish connection, the sender and receiver does not know when they will get their next packet) and best effort delivery (no g'teed of reliable packet delivery, different packets may take different paths). It is media independent (can travel through cooper cable, optical fibre, radio etc)

The most important information in the IP header is Source Address, Destination Address, TTL and Service Type. Fragment Offset inform the user if the packet is part of a larger packet.

A switch extend the broadcast domain while a router divide the broadcast domain.

A network is often divided into sub-networks for a few reasons - To increase security and restrict access from other sub-networks or to reduce the broadcast domain so that broadcasts are contained.

Hosts within the same network may know how to communicate with one another. However, in order to access external networks, a default gateway must be used.The default gateway is another name for the router. The router accepts ip packets, analyze its destination address and determine how to forward the packet.

The ip address is divided into 2 portions. The network portion and the host portion. The network portion is used for routing by the router while the host portion is used to identify the hosts.

As long as the packets are destined for external networks, the packets are forward to the nearest router.

In the routing table, the destination network addresses and the next hop address or exit interfaces are indicated. When a packet arrive, the frame is stripped and the packet is extracted. The destination ip address is analyzed and compared to the routing table. If there is a match, then the frame is re-encapsulated and send to the correct interface. If there is no match, the packet is dropped.

There are 3 types of routes - static routes, dynamic routes and default routes. Static routes are manually configured by users, dynamic routes are created by routing protocols while default routes are created by users and are often known as routes of the last resort.

Chapter 5 slides uploaded

Hello ! The presentation slides for Chapter 5 are as follows:

Summary Slides (Beginner)
https://www.dropbox.com/s/1zkvsadocf3fsz7/Chapter_5_Overview.ppt
Slightly Detailed Slides (Intermediate)
https://www.dropbox.com/s/8vnenorn5gs9iyu/Expl_NetFund_chapter_05_Net_Layer.ppt
Detailed Slides (Advanced)
http://ibizzone.ite.edu.sg/elearning/mod/resource/view.php?id=1294
Quiz
http://ibizzone.ite.edu.sg/elearning/mod/quiz/view.php?id=1303

Follow your skill level and go through the slides. If you feel comfortable, go through the higher level slides as well and finally, attempt the quiz