1. 1 IK1500 Communication Systems IK1330 Lecture 3: Networking Anders Västberg vastberg@kth.se 08-790 44 55

2. HT08/P1IK15002 Content Elements of networking –Multiplexing –Switching –Routing –Network management (not discussed in this course). Problem solving

3. HT08/P1IK15003 Distributed information applications source/sink Distributed information applications

4. HT08/P1IK15004 Examples of Sources/Sinks Sources –Telephone –Video cameras –Files on a disk Sinks –Telephone receivers –Television monitors –Computer storage devices

5. HT08/P1IK15005 Layered Model

6. HT08/P1IK15006 Layered Model Information Services –e.g. Packet telephony, electronic mail, www Networking –Quality of Service requirements –Resource sharing Communication Links –Regarded in this course as imperfect bit-pipes: They can delay, lose or modify the information they carry

7. HT08/P1IK15007 Quality of Service Certain Quality of Service (QoS) e.g. in terms of: –Guaranteed bounds of service denial –Statistical bounds of service denial –Information loss –Throughput –Delay

8. HT08/P1IK15008 Design Perspectives Communication Link –Highest possible bit transmission rate (given the resources used) –Acceptable bit rate Networking –QoS requirements for the flows may be different for different applications: Short delay but can tolerate higher bit error rates Reliable transfer and high throughput

9. HT08/P1IK15009 Comparison: Networking – OS Protocols

10. HT08/P1IK150010 Functional Elements Multiplexing Switching Routing Network management

11. HT08/P1IK150011 Multiplexing Circuit Multiplexing –Link transmission rate is divided into channels –Each conversation gets one channel and holds that channel for the duration of the connection –Rate is fixed at connection setup time –If there are no available channels then the new communication reqeust is blocked Main performance objectives: –Probability of blocking –Handling of different classes of flows

12. HT08/P1IK150012 Circuit multiplexing

13. HT08/P1IK150013 Traffic Flow

14. HT08/P1IK150014 Multiplexing Packet Multiplexing –Average rate must be less than the bit rate of the link –Peak rate can exceed the link’s bit rate Excess data must be queued  delay If the buffer is to small  data loss –Overhead Header (and in certain cases a Trailer) Main performance objectives: –Low probability of loss –Bounded delay

15. HT08/P1IK150015 Packet Multiplexing

16. HT08/P1IK150016 Multiplexing Taxonomy multiplexing circuit multiplexedpacket multiplexed centralizeddistributed random access polled access reservation access token passingmaster-slave

17. HT08/P1IK150017 Centralized Packet Multiplexing Terminal Host Multiplexer multiplexer ports full-duplex link

18. HT08/P1IK150018 Distributed Packet Multiplexing link Nodes Random Access

19. HT08/P1IK150019 Polling Based Distributed Packet Multiplexing

20. HT08/P1IK150020 Reservation Based Distributed Packet Multiplexing

21. HT08/P1IK150021 Hybrid Link Multiplexing

22. HT08/P1IK150022 Six-Node Network linksN links

23. HT08/P1IK150023 Switch

24. HT08/P1IK150024 Switch Functionality Demultiplexing each flow Determine the output link for the flow Forward (switch) the element of each flow to the right output link

25. HT08/P1IK150025 Packet Switch Store-and-forward –Receive the entire packet first, then forward it Cut-through –Start forwarding the packet as soon as it arrives

26. HT08/P1IK150026 Packet Switch O/p Queue scheduling, processing O/p queue scheduling, processing Control and signaling functions Switch fabric Queueing and scheduling Queueing and scheduling Input processing and forwarding Input processing and forwarding Line interface Line interface Line interface Line interface

27. HT08/P1IK150027 Call Setup Procedure for a Circuit Multiplexed Network

28. HT08/P1IK150028 Operation of a Circuit Switch

29. HT08/P1IK150029 Routing Establish paths through the network between sources and sinks Difference between routing and forwarding Two types: –Centralized Routing –Distributed Routing

30. HT08/P1IK150030 Routing Routing Algorithms –Find end-to-end path through the networks –While: Fulfilling QoS constraints Utilize network resources efficiently Two main types: –Hop-by-Hop routing –Source routing

31. HT08/P1IK150031 Packet Multiplexed Network Virtual circuit-based –Routes are determined at the connection setup time –Sufficient to know the label of the connection and not the complete source and destination address Datagram-based –Each packet is routed separately –Each packet must know the source and destination address