Diffserv: Can it coexist with neutrality?

One of the managers at AT&T recently blogged about (AT&T Public Policy Blog: The Danger of Dogma) an IETF working group’s RFCs regarding Diffserv, a traffic classification scheme, as evidence that neutrality is not a fundamental principle of the internet.  I’m pondering, in brief, whether Diffserv and neutrality can coexist, and if so, how.


Briefly, Diffserv adds a small tag to each datagram in order to classify its type of service.  The default is the standard best-effort, and other options are for various priorities in order to help guarantee that specific traffic will reach its destination in a useful manner.  The scheme depends on intermediaries respecting the tag on each datagram, and being able to actually carry out the request according to its meaning.  The old scheme, best-effort, simply means that each intermediary treats each datagram the same, and tries to faithfully route it on toward its destination.

A Mixed Bag

So, if you have a bag of marbles, and they are all the same size, then reaching in, you will be equally likely to grab any of them.  It could be said they have neutral weight with respect to one another.  The Diffserv bag contains many marbles that are equal, but some are bigger, and some are sticky.  You are more likely to pull some of those marbles out.  That much is obvious, and there will be an inherent bias there.  Is that necessarily a problem?

I am willing to admit it is not necessarily a problem.  If you have upgraded your marble scoop to be faster (ie, you can guarantee the same treatment as always to the standard marbles), then there’s really nothing wrong with the bigger marbles being mixed in.

The Rub.

We are talking about the data services industry.  They are not known for their dependability, and even if they swore on a stack of IETF STD docs that their new marble scoop would not only guarantee the old level of treatment to standard marbles, but would actually do better, I would not believe them out of hand.  That much is clear.

So, we have a question to ask them.  What, exactly, will be the technical measure that will guarantee the continued progress of the network, and how will you be deterred from simply keeping the infrastructure static while wink-nudging customers into adding stickum to their datagrams?  That’s what it will take to make such a change acceptable to those of us that aren’t in your pockets: undeniable proof, based on well established standards of evidence that are employed in this little thing called science.

What Proof Could Look Like

Proof that they would not discriminate against best-effort packets would have to come in the form of infrastructure guarantees.  That is, they would have to make public commitments to their infrastructure development.  Furthermore, random, public audits showing consistent improvement in the delivery of best-effort datagrams would be required by law to show a lack of bias.

The penalties for cheating or non-participation in the audits would have to be very stiff and actually enforced.  As the government doesn’t enforce the law for extraction of resources from ecologically sensitive environments, Diffserv doesn’t look very promising.