How traffic shaping works, part 2

Continuing on from my previous post, we can see that in a packet switching network, data goes from point A to point B with no regards to the type of data being carried.  Various algorithms compute the best path with no regards for the type of traffic being transmitted.  If a protocol is SMTP, HTTP, FTP, or something else, the next node doesn’t matter.  The transmission algorithm computes the fastest way in order to ensure that the data gets there and its integrity is retained.

Net Neutrality requires that the transmission entity – companies like Verizon, AT&T or Comcast who own the cable lines – route traffic like this and don’t change anything.  In other words, the they continue to look at the Sender, Receiver, protocol and packet number and send traffic the best way possible regardless of what that protocol is and regardless of what the payload is.

Where traffic shaping comes into play is the cable provider doing more packet inspection.  Not only do they need to know the routing information (like for all traffic), they also inspect the content of the traffic to make decisions.  Suppose that a user is sending an email to a friend, and that the friend is also downloading bit torrents.  A cable provider might deduce that sending email is a fairly lightweight operation because we can only write so many emails and most messages are small.  By contrast, bit torrents are much bigger.  Someone might be trying to download a pirated version of Avatar.  Movies are very, very large and they consume a lot of bandwidth.  Most emails are less than 100kb.  Most movies are 3-4 gigabytes.  This sucks up a lot of the providers bandwidth.  Suddenly, the cost to the provider increases and before what was a formerly feasible service (providing Internet service to end users) has become infeasible. 


A provider has to lay down more and more infrastructure to accommodate the bit torrent downloader in order to ensure that the quality of service to its other users is not degraded.  Yet, it charges the user the same amount of money (or only marginally more).  This increased set of costs on the cable provider starts to become infeasible when more and more users start using substantially large amounts of bandwidth yet the cable provider sees no derived benefit from it.  In order to remain competitive (and stay in existence), they need to keep their costs down.

In order to get around this increased demand from users for bandwidth, cable providers do something called deep packet inspection.  Instead of only looking at the routing information, they also look at the payload.  If the payload happens to be something that they deem to be bandwidth heavy, such as bit torrent’ing, then they might decide to do one of the following:

  • Throttle the connection – wherein the bandwidth provider slows down the traffic speed from point A to point B.  Rather than pushing it all through at once, the bandwidth provider limits the rate at which it transmits data between the two end points.

  • Alternate routing – wherein the bandwidth provider looks at the type of data being transmitted, and routes it to an alternate path that is lower quality.  The net effect is the same as throttling, the speed and reliability at which the two end points can exchange data is degraded.

Depending on who you ask, this is either reasonable behavior (the cable companies and hardware infrastructure companies) or completely unreasonable (users and software companies).  Where the Net Neutrality debate starts to get heated is when the headers of packets are inspected and routing decisions are made based upon the source of the content, rather than the type of the content.

If you watched the videos in my other post, the concern is that if a user subscribes to Comcast, and they want to watch a TV show that airs on NBC, that’s no problem today.  But suppose Comcast and ABC have cut a deal.  Rather than transmitting data between NBC and the end user at the optimal speed, Comcast deliberately throttles the connection so that the user experience is degraded (choppy video, pauses, etc).  In response, a user says “Enough is enough” and heads on over to ABC.  “Hey, this video quality is sweet!  I’ll just stick to shows on ABC!”  Comcast wins because the deal they cut with ABC is paying off.  ABC wins because they get more viewers.  NBC loses because ABC and Comcast have cut them out of the loop.  So you see, the source/destination of the traffic and its possible throttling is what has many Net Neutralists up in arms.  They fear that large corporations can get together and collude to influence user behavior.

This is one example but there are others.  Governments can pressure ISPs to throttle connections to opposition groups.  ISPs can cut deals with each other to knock other ISPs out of the market.  Google can team up with Road Runner and provide high speed voice services (not that Google would since they are a Net Neutrality advocate).  And so forth.  If the net is neutral, that means that all cable providers can do is inspect the routing information and pass it along to the next best hop without prejudice.  Without it, they can inspect the type of payload, or the end-points of that payload, and make routing decisions that would degrade the user experience.  It would essentially mean that free information is now subject to the whims of (presumably evil) corporations who are malevolently looking to make more money off of end users, and this is against the entire spirit of the Internet which is freedom of access to information. 

Bandwidth providers reply that if they are going to lay down expensive infrastructure and people want to pay more for better access, then they should be allowed to do that.  If they can’t charge more, then why should they invest?  Free market advocates claim that enforcing Net Neutrality is a way of regulating the Internet – which the Net Neutrality advocates should be against.  They also claim that even if a few bandwidth providers do this, others will not.  End users will stop using ISPs that use traffic shaping and will flock to those that do not, and therefore the attempts by bandwidth providers to shape traffic will fail once they see that their businesses are losing money because of those policies.

It’s a complicated debate but I think I’ll reiterate my previous position – it’s about the money.

Skip to main content