Design and Implementation of Sender Initiated Congestion Control

This paper reports the design and implementation of a multicast transport-layer protocol called Sender Initiated Congestion Control (SICC) which provides adaptive flow control for multicast methods such as Application Layer Multicast (ALM) or eXplicit multi-unicast (XCAST). SICC is a NAK based protocol and is designed to be extensible to adapt to various codecs, able to handle variable length of application data units (ADU) and to notify availability of ADU at the receiver for real-time streaming. We have implemented SICC in both user space on NetBSD and kernel space on Linux 2.6.10, and have used these implementations to evaluate TCP fairness. The results show the fairly shared bandwidth with 128 competing TCP flows with 1ms timer accuracy in various RTT. We also verified the applicability to small appliance by implementing SICC/XCAST6 on a prototype network camera and evaluated SICC in a field experiment.