<s>
Compound	B-Protocol
TCP	I-Protocol
(	O
CTCP	O
)	O
is	O
a	O
Microsoft	O
algorithm	O
that	O
was	O
introduced	O
as	O
part	O
of	O
the	O
Windows	B-Application
Vista	I-Application
and	O
Window	O
Server	O
2008	O
TCP	B-Protocol
stack	O
.	O
</s>
<s>
It	O
is	O
designed	O
to	O
aggressively	O
adjust	O
the	O
sender	O
's	O
congestion	B-Protocol
window	I-Protocol
to	O
optimise	O
TCP	B-Protocol
for	O
connections	O
with	O
large	O
bandwidth-delay	O
products	O
while	O
trying	O
not	O
to	O
harm	O
fairness	B-Protocol
(	O
as	O
can	O
occur	O
with	O
HSTCP	B-Protocol
)	O
.	O
</s>
<s>
It	O
is	O
also	O
available	O
for	O
Linux	B-Application
,	O
as	O
well	O
as	O
for	O
Windows	O
XP	O
and	O
Windows	O
Server	O
2003	O
via	O
a	O
hotfix	O
.	O
</s>
<s>
Like	O
FAST	B-Protocol
TCP	I-Protocol
and	O
TCP	B-Protocol
Vegas	I-Protocol
,	O
Compound	B-Protocol
TCP	I-Protocol
uses	O
estimates	O
of	O
queuing	O
delay	O
as	O
a	O
measure	O
of	O
congestion	O
;	O
if	O
the	O
queuing	O
delay	O
is	O
small	O
,	O
it	O
assumes	O
that	O
no	O
links	O
on	O
its	O
path	O
are	O
congested	O
,	O
and	O
rapidly	O
increases	O
its	O
rate	O
.	O
</s>
<s>
Compound	B-Protocol
TCP	I-Protocol
maintains	O
two	O
congestion	B-Protocol
windows	I-Protocol
:	O
a	O
regular	O
AIMD	O
window	O
and	O
a	O
delay-based	O
window	O
.	O
</s>
<s>
The	O
AIMD	O
window	O
is	O
increased	O
the	O
same	O
way	O
that	O
TCP	B-Protocol
Reno	O
increases	O
it	O
.	O
</s>
<s>
Thus	O
,	O
unlike	O
TCP-Illinois	B-Protocol
and	O
its	O
precursor	O
TCP	B-Protocol
Africa	O
,	O
Compound	B-Protocol
TCP	I-Protocol
can	O
reduce	O
its	O
window	O
in	O
response	O
to	O
delay	O
.	O
</s>
<s>
This	O
increases	O
its	O
fairness	B-Protocol
to	O
Reno	O
.	O
</s>
<s>
Descriptions	O
of	O
Compound	B-Protocol
TCP	I-Protocol
can	O
be	O
found	O
in	O
a	O
conference	O
paper	O
,	O
an	O
Internet-Draft	O
,	O
and	O
a	O
US	O
patent	O
.	O
</s>
<s>
CTCP	O
is	O
enabled	O
by	O
default	O
in	O
computers	O
running	O
beta	O
versions	O
of	O
Windows	O
Server	O
2008	O
and	O
disabled	O
by	O
default	O
in	O
computers	O
running	O
Windows	B-Application
Vista	I-Application
and	O
7	O
.	O
</s>
<s>
Since	O
Windows	O
8	O
,	O
Windows	O
uses	O
PowerShell	B-Application
command	O
to	O
modify	O
the	O
congestion	O
control	O
algorithm	O
.	O
</s>
<s>
CTCP	O
was	O
ported	O
to	O
Linux	B-Application
.	O
</s>
