Information Technology Reference
In-Depth Information
550
0.002
M-first(M=2)
M-first(M=3)
M-first with sp
o
t-checking(M=2)
M-first with spot-checking(M=3)
Credibility-based voting(random)
Credibility
-
based voting(rr1)
ε
acc
M-first(M=2)
M-first
(
M
=
3
)
M-first with spot-c
heck
i
n
g
(
M=2)
M-first wit
h
s
p
o
t-checking(M=3)
Credibil
i
t
y
-based voting(random)
C
r
e
d
ibility-based voting(rr1)
500
0.0015
450
400
0.001
350
300
0.0005
250
0
200
0
0.2
0.4
0.6
0.8
1
0
0.2
0.4
0.6
0.8
1
s
s
(a) Error-rate
(b) Computation time
T
Figure 14.
M
-first voting with spot-checking vs. Credibility-based voting for sabotage
rate
s
(
acc
=0.001
,
f =0.35
,
c =1.0
,
q =0.1
,
p
d
=0
, random scheduling without
blacklisting).
figure shows that, even if
M =3
,
M
-FVSC can not guarantee the reliability condition,
while credibility-based voting achieves it for any
s
. It requires larger redundancy (
M ≥ 4
)
for
M
-FVSC, which results in increased computation time. Also, the computation time of
credibility-based voting is smaller than that of
3
-FVSC. This result indicates that credibility-
based voting is the most promising approach of spot-checking-based sabotage-tolerance
methods for high-performance and reliable VC systems.
0.002
550
M-first(M=2)
M-first(M=3)
M-first with spot-checking(M=2)
M-first with spot-checking(M=3)
Credibility-based voting(random)
Credibility-based voting(rr1)
ε
acc
M-first(M=2)
M-first(M=3)
M-first with spot-checking(M=2)
M-first with spot-checking(M=3)
Credibility-based voting(ra
n
dom)
Credibility-based voting(rr1)
500
0.0015
450
400
0.001
350
300
0.0005
250
0
200
0 0.05 0.1 0.15 0.2 0.25 0.3 0.35
0
0.05 0.1 0.15 0.2 0.25 0.3 0.35
f
f
(a) Error-rate
(b) Computation time
T
Figure 15.
M
-first voting with spot-checking vs. Credibility-based voting for fraction
f
(
acc
=0.001
,
s =0.1
,
c =1.0
,
q =0.1
,
p
d
=0
, random scheduling with blacklisting).
Fraction
f
Fig.15 (a) shows the error rates of each method for fraction
f
in cases with
blacklisting. This figure shows that both spot-checking-based methods guarantee the relia-
