Energy Aware VI Planning 221
t. The following demand constraints should be satisfied in the VI [27]:
s
p
a
dsi
t
m
di
≤t≤t
M
di
x
dpti
=
t≤T
h
dti
,d=1, 2,...,D,
i =1, 2,...,I, t =1, 2,...,T
(8.6)
Summing up the lightpaths through each link e (e =1, 2,...,E)ofthe
VI we can determine the required link capacity y
et
for link e required at time
t [28], [29]:
d
i
s
p
δ
edpti
x
dpti
≤ y
et
,e=1, 2,...,E, t=1, 2,...T (8.7)
where δ
edpti
is a binary variable defined as follows [28], [29]:
δ
edpti
=
⎧
⎨
⎩
1, if link e of VI belongs to path p realizing
demand d of service class i at time t at server s
0, otherwise
(8.8)
Using the same rationale, the capacity of each link e at time t in the VI
is allocated by identifying the required lightpaths in the PI. The resulting PI
lightpath z determine ...