Information Technology Reference
In-Depth Information
5
Simulation and Experimental Results
In order to evaluate the function and performance of Comb, we implemented a simu-
lator in C++. The simulator can simulate Comb system with up to 8,000 nodes.
Table 2.
Parameters and Settings of the simulation
Parameter
Value
N
1000, 2000,
4000, 8000
Total number of peers in the network
D
Total number of Domains
20, 40, 80
L
Node's lifetime
90s, 120s, 180s
F
Frequency of lookup
1, 2, 3
The simulation is configured by parameters N, D, L and F. When simulator starts
up, the Comb system contains N nodes with settled routing tables distributed in D
domains averagely, nodes join and leave the system with the lifetime L, and send out
lookup messages by every F seconds. The simulator stops when 10N nodes joined in
the system accumulatively. Parameters are configured as the table 2.
We evaluate Comb's routing efficiency by figuring out the average routing hops
and failed rate per lookup. Figure 6 plots the average number of routing hops per
lookup when varying the system size and numbers of domains. The Figure shows that
the average routing hops are always below 2 in Comb, and the number increases alone
with both the system size and domains number.
Failed lookups should also be considered for routing efficiency. In Comb simula-
tor, messages record every hop it routed through, a lookup (and also other messages)
was regarded as a failed message when it is forwarded by more than 10 peers, and
would be discarded by the simulator. Figure 7 reports the failed rate of lookups in a
variety of conditions, we see that Comb system has a satisfied failed rate, in the expe-
riment environment, failed rates are below 0.5% in all conditions.
Fig. 6.
Routing hops per lookup varying nodes' number and domains' number
