Vital Topics to be covered in this Session
- Network layer and its functions.
- Network and internetwork.
- Networking devices.
- Router.
- Hub.
- Switch.
- Gateway.
- Bridge.
- Modem.
- Repeater.
- NIC (Network Interface Card).
- Addressing and its classes.
- Masking.
- Subnetting.
- Routing and routing table.
- Routing algorithms.
- Shortest path routing--Dijkastra Algorithm.
- Distance Vector Routing.
- Link state Routing.
- Broadcast routing.
- Unicast Routing.
- Anycast Routing.
- Multicast Routing.
- Internet protocol(IP).
- IPv4 vs IPv6.
- In the seven-layer OSI model of computer networking, the network layer is layer 3.
- The network layer is responsible for packet forwarding including routing through intermediate routers, whereas the data link layer is responsible for media access control, flow control and error checking.
Functions of Network layer
- The network layer provides the functional and procedural means of transferring variable-length data sequences from a source to a destination host via one or more networks, while maintaining the quality of service functions.
Functions of the network layer include
Connection model
connection less communication
- For example, IP is connection less, in that a data-gram can travel from a sender to a recipient without the recipient having to send an acknowledgement.
- Connection-oriented protocols exist at other, higher layers of the OSI model.
Host addressing
- Every host in the network must have a unique address that determines where it is.
- This address is normally assigned from a hierarchical system. For example, you can be "Fred Murphy" to people in your house, "Fred Murphy, 1 Main Street" to Dubliners, or "Fred Murphy, 1 Main Street, Dublin" to people in Ireland, or "Fred Murphy, 1 Main Street, Dublin, Ireland" to people anywhere in the world.
- On the Internet, addresses are known as Internet Protocol (IP) addresses.
Message forwarding
- Since many networks are partitioned into sub networks and connect to other networks for wide-area communications, networks use specialized hosts, called gateways or routers, to forward packets between networks.
- This is also of interest to mobile applications, where a user may move from one location to another, and it must be arranged that his messages follow him.
- Version 4 of the Internet Protocol (IPv4) was not designed with this feature in mind, although mobility extensions exist. IPv6 has a better designed solution.
