The adaptive load service (ALS): an ABR-like service for the Internet

We present a novel approach for realizing adaptive QoS control in the Internet called the adaptive load service (ALS). ALS was designed in a similar fashion to the available bit rate service (ABR) proposed for ATM. That is, the senders transmit control messages indicating their requirements, intermediate routers adjust the indicated values in accordance with their available resources and the receivers send the contents of the control messages back to the senders. The transmission behavior of the senders is then adjusted in accordance with the indicated values in the returned control messages. Unlike ABR, ALS is IP-based and was designed to scale for large multicast groups and accommodate the needs of heterogeneous receivers through the integration of sender-based and receiver-based adaptation mechanisms in addition to relying on the network feedback for adjusting the transmission behavior. Performance tests of ALS under different simulation topologies show its efficiency in terms of bandwidth utilization and loss reduction. The tests also show ALS to be fair towards competing TCP connections. Additionally, even though ALS uses a simple algorithm for determining the fair bandwidth share a connection should be using, ALS manages to fairly distribute available resources in accordance with the max-min fairness criterion.