1. Advanced Computer Networks Classification of Access Network Types: Ethernet, Wireless LAN, ADSL, Cable Modem or Dialup? Wei Wei, Bing Wang, Chun Zhang, Jim Kurose, Don Towsley University of Massachusetts, Amherst Department of Computer Science Presented by Mark Johnson

2. Advanced Computer Networks Introduction Classify Access Network Type –Ethernet (switched and not) –WLAN –ADSL –Cable Modem –Dialup Accurate, fast classification from external location

3. Advanced Computer Networks Background 802.11b Standard WLAN –Average transmission overhead of 810ms –Wireless station must wait for random backoff DOCSIS (Cable modem) –Backoff to send request Ethernet, ADSL, and dialup –Dedicated access, no backoff

4. Advanced Computer Networks Classification Scheme Two primary measures –Inter-arrival time –Entropy Method –Send n packet pairs –Calculate population median inter-arrival ξ.5 (I) –Calculate entropies and

5. Advanced Computer Networks Classification Scheme

6. Advanced Computer Networks Analytical Basis Assumptions –Up to two low bandwidth links –M/D/1 queuing –Interarrival times at receiver are indicative of interdeparture times at sender Theorems –Ethernet median and entropy –802.11b median and entropy –ADSL, Cable, and Dialup median and entropy

7. Advanced Computer Networks Experimental Results Controlled Experiments (small scale) –Detection on known University and home connections –Results mainly as expected: median and entropies of inter-arrival times fit models

8. Advanced Computer Networks Experimental Results

9. Advanced Computer Networks Experimental Results Uncontrolled Experiments (large scale) –Bandwidth of receiver isn’t important –Results largely fit expected demarcations 5 DSL connections would erroneously be detected as WLANs –Criteria for distinguishing low bandwidth connections are not clear

10. Advanced Computer Networks Experimental Results

11. Advanced Computer Networks Experimental Results Combination of mean and entropy gives a good classification Distinguishing low speed (ADSL, Cable, dialup) connections is not straightforward Connections with a large median usually have a large entropy