Experiences with Unicast/Multicast Tutorials and International Classes at the University of Alabama in Huntsville Robert L. Middleton, P.E. Senior Research Engineer University of Alabama in Huntsville Richard T. Bagwell Senior Network Engineer Alabama Research and Education Network Background • The Huntsville based National Center for Children’s Advocacy wanted an Internet based replacement for their Satellite based Tutorials • UAH Internet based streaming video and synchronized PowerPoint slide approach viewed as probable replacement. Requirements • High quality Video and Audio • Multiple formats of Video • Mixture of pre-recorded and live video to enable remote site Q/A session • No new equipment at remote sites • Pre-scheduled start and stop times • Delivery to a large number of paying sites • Security Approach • Simultaneous Multicast and Unicast from our server over both Internet 2 and Internet • Microsoft’s Producer enabled recording and placing video/text material on a timeline. • Internet Explorer and Windowsmedia Player free downloads for remote sites • Windowsmedia Server capable of all desired features Network configuration • Both UAH and AREN Networks needed some upgrading to accommodate Multicast • Current streaming video server with MS Windowsmedia Sever software OK • Extensive testing of Multicast/Unicast to remote sites performed Tutorial Delivery • Lobby site had countdown clock and test video for last pre-check • Remote sites joined either a multicast or unicast “Lobby” site 15 Min. prior to start. • Start to finish of tutorial (~2.5 Hrs), including Live q/A session, remote sites were on “autopilot” and required no attention, as on TV. Demonstration Tutorials • National Children’s Advocacy Center Tutorial #2 (October 24, 2002). • Joint Class with French Engineering School ESTACA (February 2003) A Few Technical Issues with Producer™ Multicast Deployment • • • • Multicast Group address space Software Version/Compatibility Issues Campus Networking Challenges Inter-domain Multicast Magic Multicast Address Space • Microsoft Producer™ uses randomly assigned Multicast group addresses • During initial testing, Microsoft defaults were used • We began to worry that Producer™ was not reserving these addresses with any central authority • The addresses could be overlapping with other applications (such as the legacy Mbone tools and Cisco IPTV) that can use SDR to reserve group addresses • Although this overlap may not cause application problems, it could result in unwanted traffic. GLOP Addressing • RFC3180 “GLOP Addressing in 233/8” • Current best practice is to use multicast address space that is derived from your AS number • Provides a single /24 of multicast address space per AS • UAH manages their GLOP addressing using their existing Unicast address inventory tool • Dynamic assignments can be made via an extension to DHCP called “MADCAP” [RFC2730] in the future UAH’s GLOP Space UAH Autonomous System Number: 10364 10364d = 00101000 01111100b 00101000b = 40d 01111100b = 124d AS 10364 22.214.171.124/24 Troubleshooting IP Multicast Functionality of Microsoft Producer™ • Problems Encountered – Client Software Version Issues – Campus Multicast Complications – Wide Area Inter-domain Multicast Problems Client Software Issues • Producer™ relies on Internet Explorer (IE) and Windows Media • Only foolproof configuration: Clients running XPpro operating system with updated Windows Media and IE • Good but spotty results with Win2K and Win98SE machines with updated Windows Media and IE • Use of XP was encouraged in testing since its used removed at least one possible problem from our troubleshooting list Campus Multicast Complications • UAH campus infrastructure upgrade (ATM to GigE) coincided with our multicast testing – Initially had to disable mls for multicast on campus 6509 Layer3 switch/router. • Testers outside Alabama often were unaware if IP Multicast was enabled on their local networks • Initial troubleshooting tool was Cisco IPTV – attempting to view NASA clips from OR • Best tool found: Internet2 Detective Internet2 Detective • http://detective.internet2.net/ • Test connection to Abilene • Test if subnet is Multicast Capable • Don’t need to call campus IT folks Wide Area Inter-domain Multicast Troubleshooting • IP Multicast on Abilene currently relies on a combination of three protocols – PIM-SM, MBGP, MSDP • Problems were encountered when BGP used non-multicast capable links for traffic between UAH and AREN NOC – Solved by judicious use of BGP filtering • The BGP issue was a direct result of topology of network in Alabama Alabama Logical Network Topology (GCG and AREN) AREN-Hsv Router UAH/GCG Router I1 BGP PVC I2 BG P C PV SoX Router UA/GCG Router AREN-Bham Router UAB/GCG Router Inter-domain Multicast Troubleshooting Tools • The most useful tool for troubleshooting: Router show commands – We had direct access to AREN, UAH, and GCG routers. • Abilene routers accessed trough the “Abilene Core Node Router Proxy” – http://www.abilene.iu.edu/tools.html Most Common Troubleshooting Commands for Cisco Routers Router# show ip mroute Router# show ip msdp peer provides a look at the Multicast routing table shows peer state, traffic, and filters Router# show ip msdp sa-cache shows the “service advertisement” cache and allows you to confirm msdp is correctly advertising sources. Confirms multicast routes are active (and tons of other stuff) Confirm PIM domain config is joining correctly Router# show ip bgp neighbor Router# debug ip pim 126.96.36.199 Summary and Conclusions • High quality Education and Training can be delivered to Internet 2 (and extensions) connected Schools in both live and asynchronous formats via Unicast/Multicast • Campus LAN Traffic inhibits Multicast video • Time zone differences encourage asynchronous Unicast delivery Summary & Conclusions 2 • Many Universities who tested our NCAC Tutorials, could receive the Multicast material, but most elected the Unicast option. • “Homeland Defense” communication needs may advance Multicast capabilities. • For more info on UAH efforts, our “Case Study” is available from Microsoft’s website Closing Credits • • • • • • • UAH Computer & Network Services AREN NCAC Microsoft Producer and Windowsmedia Teams Dr. Robert Frederick (IPT Classes) Dr. Bill Kearns- Dir. USF-DMHC (pilot testing) Mr. James A Williamson Jr.- UAH Graduate Asst.
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