<s>
In	O
queueing	O
theory	O
,	O
a	O
discipline	O
within	O
the	O
mathematical	O
theory	O
of	O
probability	O
,	O
a	O
layered	B-Operating_System
queueing	I-Operating_System
network	I-Operating_System
(	O
or	O
rendezvous	B-Operating_System
network	I-Operating_System
)	O
is	O
a	O
queueing	O
network	O
model	O
where	O
the	O
service	O
time	O
for	O
each	O
job	O
at	O
each	O
service	O
node	O
is	O
given	O
by	O
the	O
response	O
time	O
of	O
a	O
queueing	O
network	O
(	O
and	O
those	O
service	O
times	O
in	O
turn	O
may	O
also	O
be	O
determined	O
by	O
further	O
nested	O
networks	O
)	O
.	O
</s>
<s>
Layered	O
queueing	O
has	O
applications	O
in	O
a	O
wide	O
range	O
of	O
distributed	B-Architecture
systems	I-Architecture
which	O
involve	O
different	O
master/slave	B-Operating_System
,	O
replicated	O
services	O
and	O
client-server	B-Operating_System
components	O
,	O
allowing	O
each	O
local	O
node	O
to	O
be	O
represented	O
by	O
a	O
specific	O
queue	O
,	O
then	O
orchestrating	O
the	O
evaluation	O
of	O
these	O
queues	O
.	O
</s>
