Wireless ATM
Adaptive Voice/Data

Implementation of a Congestion Control Scheme for Active Narrowband ATM Networks

Sachin Sheth


Narrowband integrated audio/data networks require bandwidth management techniques to be implemented during congestion to provide the desired quality of service. Traditionally, congestion control schemes are applied generically and broadly at congested nodes. This can be improved by using Active Networks which provide application-specific processing of user data at congested nodes. Each application specifies how losses to the data it is processing should occur in a controlled fashion, while maintaining the desired quality of service. In this work, the Active Network architecture is implemented for a Narrowband ATM network. Switching is provided using a software switch on a computer running Linux Operating system. Congestion control programs are inserted into the switches dynamically using on-demand loading. The effectiveness of this design is demonstrated by implementing a bit-dropping congestion control algorithm for audio coded using Sinusoidal Transfer Coding (STC), encapsulated according to Real-time Transport Protocol (RTP) standards. Additional algorithms, such as RTP Header Compression are also implemented and demonstrated. The experience and results suggest that using Active Networking for congestion control allows enabling of schemes not possible within a conventional network.

Send comments to Joseph B. Evans, evans@ittc.ku.edu .