<s>
Blue	O
is	O
a	O
scheduling	O
discipline	O
for	O
the	O
network	B-Application
scheduler	I-Application
developed	O
by	O
graduate	O
student	O
Wu-chang	O
Feng	O
for	O
Professor	O
Kang	O
G	O
.	O
Shin	O
at	O
the	O
University	O
of	O
Michigan	O
and	O
others	O
at	O
the	O
Thomas	O
J	O
.	O
Watson	O
Research	O
Center	O
of	O
IBM	O
in	O
1999	O
.	O
</s>
<s>
Like	O
random	B-Algorithm
early	I-Algorithm
detection	I-Algorithm
(	O
RED	O
)	O
,	O
Blue	O
operates	O
by	O
randomly	O
dropping	O
or	O
marking	O
packet	O
with	O
explicit	O
congestion	O
notification	O
mark	O
before	O
the	O
transmit	O
buffer	O
of	O
the	O
network	B-Protocol
interface	I-Protocol
controller	I-Protocol
overflows	O
.	O
</s>
<s>
The	O
main	O
flaw	O
of	O
Blue	O
,	O
which	O
it	O
shares	O
with	O
most	O
single-queue	O
queuing	B-Application
disciplines	I-Application
,	O
is	O
that	O
it	O
does	O
not	O
distinguish	O
between	O
traffic	B-Operating_System
flows	I-Operating_System
,	O
but	O
treats	O
all	O
flows	O
as	O
a	O
single	O
aggregate	O
.	O
</s>
<s>
Stochastic	B-Protocol
fair	I-Protocol
Blue	I-Protocol
(	O
SFB	O
)	O
is	O
a	O
stochastically	O
fair	O
variant	O
of	O
Blue	O
which	O
hashes	O
flows	O
and	O
maintains	O
a	O
different	O
mark/drop	O
probability	O
for	O
each	O
hash	O
value	O
.	O
</s>
<s>
Unlike	O
other	O
stochastically	O
fair	O
queuing	B-Application
disciplines	I-Application
,	O
such	O
as	O
SFQ	O
(	O
Stochastic	O
Fairness	O
Queuing	O
)	O
,	O
SFB	O
can	O
be	O
implemented	O
using	O
a	O
bloom	B-Algorithm
filter	I-Algorithm
rather	O
than	O
a	O
hash	B-Algorithm
table	I-Algorithm
,	O
which	O
dramatically	O
reduces	O
its	O
storage	O
requirements	O
when	O
the	O
number	O
of	O
flows	O
is	O
large	O
.	O
</s>
<s>
A	O
resilient	O
stochastic	B-Protocol
fair	I-Protocol
Blue	I-Protocol
(	O
RSFB	O
)	O
algorithm	O
was	O
proposed	O
in	O
2009	O
against	O
spoofing	O
DDoS	O
attacks	O
.	O
</s>
<s>
An	O
implementation	O
of	O
Blue	O
is	O
part	O
of	O
ALTQ	B-Algorithm
,	O
the	O
network	B-Application
scheduler	I-Application
for	O
BSD	O
Unix	O
.	O
</s>
<s>
An	O
implementation	O
of	O
SFB	O
for	O
Linux	B-Operating_System
was	O
included	O
in	O
the	O
Linux	B-Operating_System
kernel	I-Operating_System
in	O
version	O
2.6.39	O
.	O
</s>