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

2. 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

3. 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

4. 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

5. 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)

6. 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

7. 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( )/3
Binomial CC s.t. k+l =1 and l<=1, for
suitable values of and  
S / (R p )

8. 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( )/3
and < 0.5