1. Traffic Characterization Dr. Abdulaziz Almulhem

2. Almulhem©20012 Agenda Traffic characterization Switching techniques Internetworking, again.

3. Almulhem©20013 Characteristics of Traffic Traffic arrival rate and variability Connection duration Distribution of message length Allowable delay and variability of delay Required reliability

4. Almulhem©20014 Traffic Patterns Traffic patterns are generated due to: User behavior Application behavior

5. Almulhem©20015 Traffic Patterns User behavior Access session start Choice and usage of application Tariffing has impact on user behavior

6. Almulhem©20016 Traffic Patterns Application behavior Size distribution of Email, HTTP page, FTP file Packet traffic due to TCP connection management TCP acknowledgments Authentication or other protocols Stream flow control

7. Almulhem©20017 Dial-Up Access to WWW Client Server Dial-up Access Session App1 App2 App3 Dialogue Connection Bursts Packets Cells Access session level (min-hrs) Application session level (min-hrs) Dialogue level (sec-min) Connection level (ms-min) Burst level (  s-s) Packet level (  s-s) Cell level (ns-  s)

8. Almulhem©20018 Interesting Statistics on WWW 10% of all Web sessions are longer than 3 hrs 60% of all connections are shorter than 10 sec.

9. Almulhem©20019 Examples of Traffic Types Interactive terminal-to-computer sessions low message rate message length short delay requirement moderately strict required reliability high

10. Almulhem©200110 Traffic Examples (cont.) File transfer sessions message rate low message length very long delay requirement very relaxed required reliability very high

11. Almulhem©200111 QoS requirements of different types of traffic

12. Almulhem©200112 QoS Scale

13. Almulhem©200113 Circuit Switching When session is set up, path is chosen and bandwidth allocated on each link (by FDM or TDM). If no path with sufficient BW, call is rejected Advantage: once call is accepted, BW is guaranteed; no queuing Disadvantage: inefficient utilization of transmission capacity if traffic is bursty

14. Almulhem©200114 Packet Switching Store and forward Statistical multiplexing No fixed allocation of BW Packets from different sessions combined into single queue for each outgoing link Full transmission capacity of link dedicated to single packet Advantage: full utilization of link capacity whenever traffic is present

15. Almulhem©200115 Connectionless versus Connection-Oriented Routing Virtual circuit routing connection-oriented fixed path (but not fixed BW) assigned at start of session; all packets follow same path Example: ATM Datagram routing packets in session are routed independently Example: IP

16. Almulhem©200116 Internetworking Heterogeneous working platforms Two important functions: Fragmentation and reassembly Encapsulation/decapsulation

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