Rational solutions to ease congestion

Ivan Pepelnjak
06 Aug 2009

The transition to widely available broadband internet has dramatically changed the behavior of some end-users who consume inordinate amounts of bandwidth. The unexpected rise in demand from these users invalidated residential internet business models and forced service providers to introduce network congestion and traffic management practices, the most controversial of which is deep packet inspection (DPI), and sometimes go as far as introducing traffic caps on users.

The tug-of-war between a small percentage of bandwidth-abusing users and service providers has escalated into a full-scale conflict in terms of how much bandwidth users are paying for and what constitutes abusing the network. Bandwidth management issues that have come to the surface include cable operators trying to stop third parties from delivering video over their infrastructure, regulatory actions to oversee traffic management policies, and congressional hearings on broadband services. Add users who hog bandwidth and carriers that perform covert traffic management actions to that explosive mix -- the most infamous being the Comcast peer-to-peer (P2P) packet monitoring incident -- and you have all the necessary ingredients for a good technology soap opera.

The whole traffic management issue would be a gripping tragicomedy if it didn't affect the performance of the Internet, a vital piece of mission-critical infrastructure.

How we got here from there

Before broadband Internet technologies (cable, DSL and fiber) were introduced, almost all residential Internet services were based on dial-up access, which contains an implicit usage model: the longer you are connected, the larger your phone charges. Even when ISPs offered flat-rate services and there were no hidden charges, access speeds were so low that average line utilization closely matched maximum line speed.

The dial-up access model also provided clear separation between individual users, so their traffic mixed only on backhaul and transit links. The limited number of dial-in ports at each point of presence (POP) represented another bottleneck that limited core network congestion.

Fast-forward a few years to the broadband explosion, where the landscape has changed dramatically.

Numerous service providers offer broadband access that uses shared media (cable). The bandwidth of the access link is shared by many users, and a single misbehaving user can affect the whole segment.

The average bandwidth consumption has not grown in proportion to increased access-line speeds. It's hard to stress a 10 Mbit connection when you're reading email, chatting on IM, commenting on friends' Facebook photos or even watching YouTube videos.

Users are online all the time, and the dial-up port barrier has been busted.

Furthermore, ruthless competition among providers has eroded most of the profit margin, and they are forced to utilize large access-to-backhaul and even larger access-to-transit oversubscription ratios.


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