Information Technology Reference
In-Depth Information
run NOX. In addition, we use the Cassandra single PC mode and all the sub networks
are connected by EWBridge. We use the topology viewer application to fetch the entire
topology of all the sub-networks again. The results are shown in Figure 6.
Fig. 6.
Performance of DHT and EWBridge for data synchronization
As shown in Figure6, the heterogeneous EWBridge system with has two obvious
advantages: (1) Low time delay. Once receives the requests from applications, the
entire system can respond very quickly. Because in the EWBridge, each database
stores the entire network topology locally, while the DHT mode database stores the
entire network topology in distributed database located in different places. When a
DHT database node receives a data request, it has to fetch other data from different
places and then assemble all the data and then return it to the application. (2) For a
same size topology, the EWBridge system can finish all the data transmission earlier
than the DHT system. That is because the DHT system is a little slower at connection
setting up in the very beginning. So it needs longer time to finish transmission. Besides,
the EWBridge system can enable different NOSes to cooperate.
4.2
Innovativeness
According to the best of our knowledge, this is the first time to propose different
NOSes working together, in the open source community, to encourage third-parties to
engage in contributing to the NOS to promote competition and coexistence in the
NOS's environment.
4.3
Performance Analysis
DHT is a well-received storage for distributed controller at present. In this section we
analyze the performance of EWBridge by comparing it with DHT.
Speed of Network view updates.
EWBridge adopts the subscribe/ publish model.
Usually, all the peers are in the established TCP connection state. Once a network view
changes in a domain, the controller directly pushes the change to their peers with
time
returnt
. Each controller stores the global network view. The APPs can directly
access the data in local storage. For the DHT storage, entire network view is in distributed
locations. The DHT needs to fetch the data. So the time is
requesttreturnt
.
Thus, EWBridge is
requestt
faster than DHT.
