Date Added: Aug 2011
This paper proposes a purely passive method for inferring a congestion map of a network. The congestion map is computed using the congestion markings carried in existing traffic, and is continuously updated as traffic is received. Consequently, congestion changes can be tracked in a real-time fashion with zero traffic overhead. Unlike active congestion reporting methods, the authors' novel passive method is more robust during periods of congestion because there are no congestion report messages that could be lost and existing congestion is never aggravated.