A Flexible, QoS-Aware IP/ATM Adaptation Module
Key: Sch99-1
Author: Jens Schmitt
Date: December 1999
Kind: @techreport
Abstract: Overlaying IP-based networks onto ATM subnetworks is a network configuration pattern found increasingly often. While IP networks traditionally only offer plain "best-effort" service they are now evolving to offer more sophisticated services. Nevertheless, the exact mechanisms for providing QoS are not yet settled and essentially non-existing in today's production-level networks, with the Internet being the most popular and important example. On the other hand, ATM networks have been designed from their inception to offer a wide range of QoS mechanisms. Thus, given the configuration of an IP overlay network over an ATM subnetwork, it is very attractive to leverage ATM's QoS mechanisms to alleviate IP's QoS problem, at least partially. The invocation of those mechanisms will be done on so-called IP/ATM edge devices which are exactly at the frontier between the IP and ATM network. In particular, these edge devices could map reservation requests within the context of the RSVP/IntServ architecture onto especially setup VCs. In this report we describe the design and implementation of a flexible, QoS-aware IP/ATM adaptation module. This adaptation module allows an IP/ATM edge device to route IP datagrams depending on their contents onto especially setup VCs in a performant manner. To achieve performance it is necessary to implement this module in kernel space, at least partially. On the other hand, it should be easy to use, for e.g. an RSVP/IntServ over ATM, or a DiffServ over ATM mapping module. Therefore, the adaptation module was split into two parts, a kernel-level part that handles all the time-critical tasks of data forwarding and a user-level part which gives access to the functionality provided by the adaptation module. The result is a very flexible and general IP/ATM adaptation module that can be integrated conveniently with earlier results of the project on approaches of how to map the RSVP/IntServ mechanism onto those of an ATM subnetwork.
View Full paper (PDF) | Download Full paper (PDF)

The documents distributed by this server have been provided by the contributing authors as a means to ensure timely dissemination of scholarly and technical work on a non-commercial basis. Copyright and all rights therein are maintained by the authors or by other copyright holders, not withstanding that they have offered their works here electronically. It is understood that all persons copying this information will adhere to the terms and constraints invoked by each author's copyright. These works may not be reposted without the explicit permission of the copyright holder.