1 CS 240: Network Routing Michalis Faloutsos

2 Class Overview Expose you the general principles and highlight some interesting topics in routing Background in networks is necessary The class is project based Given interest/participation, we will skip the quiz Participation is required Ideal for people that want to get involved in networks research See my web page for more information

3 Use The Blackboard Update your to receive updates Check your grades through there

4 What is Routing?

5 Routing Routing is the necessary functions to ensure that data from one “host” will reach another “host” The role of routing starts once the data leaves the first communicating entity Simply put, routing is responsible for finding, establishing and maintaining communication the path

6 Routing and Layers Routing takes place at the network layer Routing is under the transport layer Routing is “unaware” of end-to-end issues (always?) Routing is above the link layer Communication between adjacent nodes happens application transport network link physical application transport network link physical Routing

7 Toy Routing Example Alexandros wants to talk to Biswanath Routing determines and uses the orange path Is this a good path? A B

8 Routing is Critical For me, routing is the most fundamental networking function It is also the most fun part in networking What makes it interesting: There are many conflicting trade-offs Routing operates with partial or out-of-date knowledge It has to handle changes and failures More recently, it has to handle mobility

9 Requirements in Routing Scale to large networks, many users Robustness: deal with changes Fault-tolerance: deal with failures Use resources efficiently: accommodate more Provide Quality of Service (QoS) guarantees

10 I. Routing View: Optimization Given a graph with weights Each edge may have more than one weight, cost, delay Find a path that optimizes some criteria A B

11 II. Routing View: Functional Routing can support several communication needs Unicast or point-to-point routing Multicasting: One-to-many, i.e. video distribution Many-to-many, i.e. teleconference Reporting: Many-to-one, i.e. sensor network Broadcasting: one to all Anycasting: one to some

12 III. Routing View: Hierarchical Following the Internet hierarchy Autonomous Systems: an network managed by a single authority, e.g. an Internet service provider (ISP) Intradomain routing: routing within a privately owned network Interdomain routing: routing between domains Different capabilities and criteria: Intradomain: full control, interest to optimize resources Inerdomain: distributed, focus on scalability and policy (BGP)

13 IV. Routing View: Network Specific Internet routing Static hosts Mobile hosts ATM routing Ad hoc network routing: everything moves Sensor networks: reporting

14 Some of the Topics Routing as an optimization problem Multicast routing BGP routing (emphasis) Ad hoc routing Sensor routing issues

15 You Need to Start Thinking for a Topic Projects: maximum two in a team Literature surveys possible, but not full marks BGP routing: modeling, stability,performance Adhoc networks: scalable routing approaches  Current work: DART by Jakob Eriksson Theoretical work:  multicast routing  Modeling application layer multicasting