<s>
TCP	B-Protocol
global	I-Protocol
synchronization	I-Protocol
in	O
computer	B-Architecture
networks	I-Architecture
can	O
happen	O
to	O
TCP/IP	B-Protocol
flows	O
during	O
periods	O
of	O
congestion	O
because	O
each	O
sender	O
will	O
reduce	O
their	O
transmission	O
rate	O
at	O
the	O
same	O
time	O
when	O
packet	O
loss	O
occurs	O
.	O
</s>
<s>
The	O
simplest	O
technique	O
to	O
limit	O
queue	O
size	O
is	O
known	O
as	O
tail	B-Protocol
drop	I-Protocol
.	O
</s>
<s>
This	O
causes	O
problems	O
when	O
used	O
on	O
TCP/IP	B-Protocol
routers	O
handling	O
multiple	O
TCP	B-Protocol
streams	O
,	O
especially	O
when	O
bursty	O
traffic	O
is	O
present	O
.	O
</s>
<s>
TCP	B-Protocol
has	O
automatic	O
recovery	O
from	O
dropped	O
packets	O
,	O
which	O
it	O
interprets	O
as	O
congestion	O
on	O
the	O
network	O
(	O
which	O
is	O
usually	O
correct	O
)	O
.	O
</s>
<s>
When	O
these	O
delays	O
expire	O
at	O
the	O
same	O
time	O
,	O
all	O
the	O
senders	O
will	O
send	O
additional	O
packets	O
and	O
the	O
router	O
queue	O
will	O
again	O
overflow	O
,	O
more	O
packets	O
will	O
be	O
dropped	O
,	O
the	O
senders	O
will	O
all	O
back	O
off	O
for	O
a	O
fixed	O
delay	O
...	O
ad	O
infinitum	O
;	O
compare	O
with	O
the	O
thundering	B-Operating_System
herd	I-Operating_System
problem	I-Operating_System
.	O
</s>
<s>
This	O
pattern	O
of	O
each	O
sender	O
decreasing	O
and	O
increasing	O
transmission	O
rates	O
at	O
the	O
same	O
time	O
as	O
other	O
senders	O
is	O
referred	O
to	O
as	O
"	O
global	B-Protocol
synchronization	I-Protocol
"	O
and	O
leads	O
to	O
inefficient	O
use	O
of	O
bandwidth	O
,	O
due	O
to	O
the	O
large	O
numbers	O
of	O
dropped	O
packets	O
,	O
which	O
must	O
be	O
retransmitted	O
,	O
and	O
because	O
the	O
senders	O
have	O
a	O
reduced	O
sending	O
rate	O
,	O
compared	O
to	O
the	O
stable	O
state	O
,	O
while	O
they	O
are	O
backed-off	O
,	O
following	O
each	O
loss	O
.	O
</s>
<s>
The	O
consensus	O
appears	O
to	O
be	O
that	O
the	O
tail	B-Protocol
drop	I-Protocol
algorithm	O
is	O
the	O
leading	O
cause	O
of	O
the	O
problem	O
,	O
and	O
other	O
queue	B-Algorithm
size	I-Algorithm
management	I-Algorithm
algorithms	I-Algorithm
such	O
as	O
Random	B-Algorithm
Early	I-Algorithm
Detection	I-Algorithm
(	O
RED	O
)	O
and	O
Weighted	O
RED	O
will	O
reduce	O
the	O
likelihood	O
of	O
global	B-Protocol
synchronization	I-Protocol
,	O
as	O
well	O
as	O
keeping	O
queue	O
sizes	O
down	O
in	O
the	O
face	O
of	O
heavy	O
load	O
and	O
bursty	O
traffic	O
.	O
</s>
