RFC 2638 (rfc2638) - Page 2 of 26
A Two-bit Differentiated Services Architecture for the Internet
Alternative Format: Original Text Document
RFC 2638 Two-bit Differentiated Services Architecture July 1999
mechanisms. We propose an architectural framework that permits the
use of both of these service types and exploits their similarities in
forwarding path mechanisms. The major goals of this architecture are
each shared with one or both of those two proposals: keep the
forwarding path simple, push complexity to the edges of the network
to the extent possible, provide a service that avoids assumptions
about the type of traffic using it, employ an allocation policy that
will be compatible with both long-term and short-term provisioning,
make it possible for the dominant Internet traffic model to remain
best-effort.
The major contributions of this document are to present two distinct
service types, a set of general mechanisms for the forwarding path
that can be used to implement a range of differentiated services and
to propose a flexible framework for provisioning a differentiated
services network. It is precisely this kind of architecture that is
needed for expedient deployment of differentiated services: we need a
framework and set of primitives that can be implemented in the
short-term and provide interoperable services, yet can provide a
"sandbox" for experimentation and elaboration that can lead in time
to more levels of differentiation within each service as needed.
At the risk of belaboring an analogy, we are motivated to provide
services tiers in somewhat the same fashion as the airlines do with
first class, business class and coach class. The latter also has
tiering built in due to the various restrictions put on the purchase.
A part of the analogy we want to stress is that best effort traffic,
like coach class seats on an airplane, is still expected to make up
the bulk of internet traffic. Business and first class carry a small
number of passengers, but are quite important to the economics of the
airline industry. The various economic forces and realities combine
to dictate the relative allocation of the seats and to try to fill
the airplane. We don't expect that differentiated services will
comprise all the traffic on the internet, but we do expect that new
services will lead to a healthy economic and service environment.
This document is organized into sections describing service
architecture, mechanisms, the bandwidth allocation architecture, how
this architecture might interoperate with RSVP/int-serv work, and
gives recommendations for deployment.
Nichols, et al. Informational