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O pen Internet Challenges in Mobile Broadband Networks. Jennifer Rexford Princeton University http://www.cs.princeton.edu/~jrex. FCC and Open Internet. Open Internet Order (2010) Transparency No blocking No unreasonable discrimination Open Internet Advisory Committee (2012)
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Open Internet Challenges in Mobile Broadband Networks Jennifer Rexford Princeton University http://www.cs.princeton.edu/~jrex
FCC and Open Internet • Open Internet Order (2010) • Transparency • No blocking • No unreasonable discrimination • Open Internet Advisory Committee (2012) • Track effects of the Open Internet Order • Provide recommendations to the FCC • Representatives from community organizations, equipment manufacturers, application providers, venture capital firms, ISPs, Internet governance, and academia
Mobile Broadband Working Group • Mobile broadband • Increasingly crucial part of Internet access • Yet, still at an early stage of development • Special treatment in Open Internet Order • Network practice transparency • Certain “no blocking” requirements • Wider latitude for differentiated service • Three case studies • AT&T limiting the FaceTime application • Mobile apps overloading signaling resources • Carriers limiting use of Google Wallet
Apple FaceTime • High-quality video chat service • Originally available only over WiFi
AT&T and FaceTime: A Timeline • Jun’12: Apple announces FaceTime over cellular • Carrier restrictions may apply • Aug’12: AT&T limits use of FaceTime over cellular • Limited to customers with the Mobile Share plan • Sprint and Verizon announcesupport on all data plans
AT&T and FaceTime: Timeline • Aug’12: Some advocates and press denounce • AT&T is violating FCC’s Open Internet Order • FaceTime competes with AT&T’s voice/video telephony • Reasonable network management practices do not include favoring one data plan over another • Aug’12: AT&T responds in a blog posting • AT&T’s policy regarding FaceTime is fully transparent • AT&T does not have a competitive video chat app • FCC rules don’t regulate availability of preloaded apps
AT&T and FaceTime: A Timeline • Sep’12: Public interest groups respond • Announcing intent to file a formal FCC complaint • Oct’12: AT&T customer files an FCC complaint • Blocking of FaceTime on his “unlimited” data plan • Nov’12: AT&T relaxes limitations on FaceTime • Supporting FaceTime on tiered plans over LTE • … though other customers would not have access
AT&T/FaceTime Issues • Pre-loaded application • Available to all users of popular phone • Accessed via device’s core calling features • High bandwidth requirements • Symmetric bandwidth usage, with asymmetric capacity • Limited adaptation in the face of congestion • Staged deployment • Rapid adoption could lead to unpredictable load • Initially limit the number of users accessing an app • Enforcement point • Usage limited on the device, not in the network
Apps With High Signaling Traffic • Signaling channel • Keeps track of mobile devices and their locations • Notifies network when a device wants to send traffic • Overloaded signaling channel • Prevents new requests from reaching the network • Can become congested before the network bandwidth • Unique issue in cellular networks • Due to Radio Resource Control function • … and the shared, constrained resources
Chatty Applications • Periodic transfers • Keep-alive messages (e.g., push services, NATs) • Polling (i.e., has something happened?) • Ad updates • Measuring user behavior • Skewed usage of signaling resources • Up to 30% resource usage for <2% traffic volume • In some cases, 90% signaling usage by one application • Also drains the battery on the phone • Machine-to-machine traffic could make this worse http://web.eecs.umich.edu/~zmao/Papers/periodic_www2012.pdf
Managing Signaling Load is Hard • End device • Strong incentives, and (some) app-level knowledge • But, incomplete control over application behavior • Application developer • Complete knowledge of own application, but not others • But, limited knowledge of the network state • Network • Sees all traffic and controls resource scheduling • But, incomplete knowledge of applications, or ability to infer app before harm has been caused
Signaling Management Challenges • Application-specific management • Adjusting timers for periodic polling • Piggybacking of requests on data traffic • Application-level signaling control • Huge number of applications • Average lifetime of 30 days and revenue of $700 • E.g., AT&T has worked with ~100 app developers • Complex optimizations • Cross-application and cross-device • Joint management of bandwidth and signaling load
Going Forward… • Network management is challenging • Large mix of rapidly evolving applications • Growing number of mobile devices • Limited bandwidth and signaling capacity • The technical details matter • Capabilities of today’s equipment • Best practices for network management • Tension between competing goals • Managing limited cellular network resources • Encouraging innovation in applications