Differentiated Services

Last updated: June-12-2001

- Introduction

New multimedia applications need real-time performance guarantees such as bounded delay and minimum throughput. The current Internet does not support these QoS parameters and it is a real challenge to integrate them in the existing architecture. The DiffServ WG is working on providing a simple schema to support various types of applications by differentiating classes of service for Internet traffic.

The differentiated services architecture proposes the use of a well-defined set of building blocks from which a variety of services may be built. In this architecture, each packet carries an information (DS byte) used by each hop to give it a particular forwarding treatment.

The major goals of the DiffServ WG are to standardize the layout of the DS byte and to assign specific forwarding treatment, called per-hop behavior, to a certain number of patterns of the DS byte, e.g. the forwarding treatment received by best-effort traffic.

Differentiated service mechanisms allow network providers to allocate different levels of service to different users of the Internet and investigations are being done on mechanisms such as traffic meters, shapers/droppers, packet markers to be used at the boundaries of the network.

Many discussions happens on the group's mailing list. Subscription requests for the DiffServ mailing list should be sent to majordomo@baynetworks.com with the line "subscribe diff-serv" in the message body. The group's mailing list itself is at diff-serv@baynetworks.com.

The DiffServ official web page is at www.ietf.org/html.charters/diffserv-charter.html.


- IETF Drafts

- Others Drafts

- Papers

- Related Papers

- ns Implementation

ns (network simulator) is a event-driven simulator developed at Berkeley. It has as front-end an OTcl interpreter and it is written in C++. Extensions to ns has been done to accomodate differentiated service architecture elements such as classifiers, markers, droppers/shapers and RIO buffer management. These extensions are currently implemented in ns version 2.1b5 using a Linux box. We are currently preparing a documentation to the use of this architecture. As soon it is finished the implementation will be publicly available at this page.