There has been a lively debate lately on the benefits or fallacy of Bandwidth-on-Demand (BoD) schemes. The bottom line is that this is a debate that has been going on since the beginning of time for all telecommunications services and it comes right down to a simple proposition: What is the fraction of the system bandwidth that is needed to meet the customer's requirement.
Let's dissect what this means. Once upon a time, the telephone represented the peak in technology for providing communications between two points and initially this represented a kind of BoD as customer could request, first through an operator request and then via a "dial", to get a circuit setup between two points. We then moved on to data communications technologies such as ISDN, X.25, and Frame Relay. Along with the Public Switched Telephone Network, these technologies enabled customers to setup defined bandwidth between customer end-points.
The reason for this allocation is straight forward, the desired allocation by a customer represented a significant fraction of the available system bandwidth. Because of this, any pure statistical best-effort system would lead to unacceptable performance to the customer. The idea of a traffic contract and end-to-end allocation of guaranteed bandwidth made it much easier to convince the customer that an end-to-end dedicated circuit, for example a switched T1 or nx64 Kbps ISDN circuit, was not necessary to ensure their application would work.
The Internet, for the most part, reflects a different approach which is the kill the problem with backbone bandwidth and ensure that user requirements are a small fraction of the network's capabilities. This all worked except that the Research and Education community has traditionally been the driving force not only in technology, but also in bandwidth use. It appeared, until the last couple of years, that the R&E community would continue this role, with networks and application requirements that spanned over 20 to 40 Gbps of nationwide cross-sectional bandwidth. As I stated in my earlier posts, the Internet bust is now over and Qwest, as well as other carriers are now faced with Internet bandwidth requirements that are growing at over 50% or more per year. So, what stagnated as a typical Tier 1 20 Gbps nationwide backbone for years is now adding that capacity every month if not significantly more - and it is accelerating.
What this all means is that public network infrastructure is growing at a huge compounded rate, and unless the R&E's requirements are growing at the same rate, the fraction of the resources of the commercial network infrastructure that R&E networks occupy will rapidly diminish. In fact, if this continues, then R&E networks will be a set of large but relatively common customers. This is true at the optical and data layers.
So, the bottom line is that commercial bandwidth capabilities are exploding and at some time in the near future R&E traffic may only be a large bump in the road leading to the conclusion that BoD (or switched multi-gigabit pipes) are not necessary. However, this is not the last word, as there are reasons other than cost that drives to creating special network services.
As I do with our customers, it is up the members of the R&E community to identify these special requirements and make an argument about why commercial network technology, or services, is not keeping pace with their needs. There are many potenial reasons, but over time the threshold for a real difference may continue to rise.
