Illustrating Networking Concepts with Wireless Handheld Devices Brad Richards & Nate Waisbrot Computer Science Department Vassar College

ITiCSE 2002, 6/24/ Project Overview Writing custom apps for Cybiko –“PDA for Kids” –Wireless communication Illustrate selected topics via hands-on lab sessions Students interact with each other through Cybiko apps –Each has a Cybiko –Participate by sending routing info, data, etc. –Process orchestrated by an administrator Funded by NSF CCLI grant

ITiCSE 2002, 6/24/ Overview of Talk Motivation & Example Cybiko Details Project Status Experiences Ongoing Work

ITiCSE 2002, 6/24/ Motivation Wanted easy way to introduce routing details Had traditionally been a lecture-only topic Was difficult to hold students’ interest –Hard to respond quickly to “what if” questions Considered using simulator –Lots of good tools available –Often much more detailed than required –Non-trivial learning curve Cybiko applications –Students enjoy interactive nature –Can arrange students to match virtual topology –Can be used in any setting

ITiCSE 2002, 6/24/ Example: Distance-Vector Routing Students can: Send short text msgs Send DVs to neighbors Ping neighbors Display routing table Clear routing table Toggle msg forwarding Also displays: Incoming text msgs Arriving DVs Details on forwarding Administrator can: Change parameters: –Split Horizon –Split w/poison reverse –Triggered Updates Force optimal routes “Kill” nodes Change NW topology

ITiCSE 2002, 6/24/ Cybiko Details Basic PDA applications Wireless RF communications (19.2 Kbps) Cheap! (US $30 for Classic) Full QWERTY keyboard Grayscale LCD display 1 MB memory (expandable) Tethers to PC to download apps, etc. Free Software Development Kit –Book also available

ITiCSE 2002, 6/24/ Project Status Routing applications finished –Flooding, Distance-Vector, Link-State Lab materials available for faculty –Source code as well Materials used with several groups: –My undergraduate Networks course, Fall 2001 –High-school students, Fall 2001 –Max Hailperin’s Networks course, Spring 2002

ITiCSE 2002, 6/24/ Experiences Did controlled study in Fall 2001 –Total of only 17 students (7 women, 7 of color) Introduced routing algorithms in lecture Gave assessment exam –Some concepts, some specific routing questions Randomly split group into two halves –8 Students got additional, more specific lecture –9 Students covered same material via Cybiko Gave same assessment exam again Both groups improved, Cybiko more –Cybiko:83  103 (24%),33% on detailed probs. –Lecture:86  100 (16%),15% on detailed probs.

ITiCSE 2002, 6/24/ Experiences (cont’d) Cybiko group wanted more examples –Both groups were asked if they wanted more –Could specify Flooding, DV, Link-State Routing –Most popular answer in lecture group: zero –Two and three were popular with Cybiko group

ITiCSE 2002, 6/24/ Experiences (cont’d) My conclusion: –Cybiko students learned at least as well –Had more fun doing it Max Hailperin’s experiences less positive –Used with 24 students –Had some hardware, user-interface difficulties We’ve worked to address most concerns –Concluded that it didn’t add anything –Still, did say: “ability to match our collective wits against reality was the strongest positive aspect”

ITiCSE 2002, 6/24/ Ongoing Work Currently working on apps for wireless NW Demonstrate contention for shared channel Hope to illustrate –Traditional Ethernet –ALOHA –WiFi (802.11) Progress slower than anticipated…

ITiCSE 2002, 6/24/ Summary Using inexpensive wireless devices Demonstrate concepts interactively Can incorporate by: –Using our applications in lab –Removing some of our code, students supply –Extend our framework in new directions See Demonstration on Wednesday

ITiCSE 2002, 6/24/