1. Network Layer
Path Determination

2. Network Layer: Path Determination
Best path thru internetwork, this enable the router to evaluate the available paths to destination.
Routing services use network topology information in evaluating network paths.
Routing uses network addresses
Uses 2 basic functions
Path determination
Switching functions

3. Routers and Data Relaying
Interface
Each interface should have a unique network or subnetwork address

4. Routed vs. Routing Protocols

5. Routed Protocols Characteristic
Has the ability to assign a network number as well as the host number

6. Routing Protocols
determine the paths that routed protocols follow to their destinations. The following are examples:
Routing Information Protocol
(RIP),Interior Gateway Routing Protocol (IGRP)
Enhanced Interior Gateway Routing Protocol (EIGRP)
Open Shortest Path First (OSPF).

7. Routing Metrics Bandwidth (Data capacity of a link)
Delay (length of time required to move a packet from source to destination)
Load (Amount of activity on a network resource)
Reliability (refers to error rate of each network link)
Hop Count (No. of passages of a packet)
Ticks (delay on a data link – approx. 35 milliseconds)
Cost (or path cost - arbitrary value assigned by an NA)

8. RIP and IGRP (Distance Vector Routing Protocol)

9. Open Shortest Path First (OSPF)

10. Multi-Protocol Routing

11. Static Routing Uses: For hiding parts of an internetwork
Allows administrator to specify what is advertised about restricted partition
To test a particular link in a network
It is the preferred method for maintaining routing tables whenever there is only one path to a destination network

12. Dynamic Routing Two functions Maintenance of routing table
Timely distribution of information in the form of routing updates
Relies on routing protocol to share knowledge
Routing protocol defines the set of rules used by router when it communicates with neighboring routers.

13. Classes of Dynamic Routing Protocols
Link State Routing (OSPF)
Approach to recreate the exact topology of the entire network.

14. Classes of Routing Protocols
Distance Vector Routing (RIP, IGRP)
Determines the direction (vector) and distance to link in the internetwork. This iterate the no. of hops in a route to find a shortest path spanning tree.

15. Comparing Distance Vector with Link State

16. Hybrid Routing

17. Other Network Services
Connectionless Network Services (Packet switch)
Connection-Oriented
(Circuit switch)