Misbehaving flows can be classified into three different types: non-TCP-friendly flows unresponsive flows using disproportionate flows

A flow that is not “TCP-friendly” is one whose throughput (in the steady state) exceeds that of any conformant TCP in the same circumstance An “unresponsive” flow is one failing to reduce its offered load in response to an increased packet drop rate A “disproportionate BW” flow is one that uses considerably more BW than other flows in a time of congestion

Misbehaving flows can cause: protocol unfairness: result from TCP flows competing with misbehaving flows the TCP flows reduce their sending rates in response to congestion, leaving the uncooperative flows to use the available BW

2. congestion collapse: - occurs when an increase in the network load results in a decrease in the useful work done by the network - first reported in October of ‘86 when the throughput of the data path from LBL to UC Berkley dropped from 32 Kbps to 40 bps

largely due to TCP connections unnecessarily - “classical congestion collapse” is largely due to TCP connections unnecessarily retransmitting packets that were either in transit or had already been received at the receiver ( inaccurate estimated RTT ) or - “congestion collapse from undelivered packet” happen when BW is wasted by delivering packets through the network that are dropped before reaching their ultimate destination (believed to be the largest unresolved danger with respect to congestion collapse in the Internet today)

TCP-equivalent Algorithms A CC algorithm is said to be TCP-equivalent if it uses AIMD to govern its transmission rate with the same increase and decrease parameters as TCP (k=0, l=1, = 1, and = 0.5) Ex several versions of TCP flavors, RAP

TCP-compatible Algorithms A CC algorithm is said to be TCP-compatible (TCP-friendly) if its steady-state throughput with the same constant of proportionality as for a TCP connection with the same packet size and round-trip time Ex AIMD (k=0, l=1) s.t. = 4(2 - 2)/3 Binomial CC s.t. k+l =1 and l<=1, for suitable values of and   S / (R p )

Slowly-Responsive Algorithms A CC algorithm is said to be Slowly-responsive (relative to TCP) if its window or rate reduction on a single packet loss or congestion notification is smaller than TCP Ex AIMD (k=0, l=1) s.t. = 4(2 - 2)/3 and < 0.5