Conference Paper

3.1
Packet Processing on the Switch
Figure 
4
shows a switch packet forwarding process. For a more accurate simulation of
the information exchanges between the switch and the controller, incoming packets were
divided in four categories; each of them is determined by specified occurrence proba‐
bility. From the switch, packets to the controller are sent using specific communication
Analysis and Performance Evaluation of SDN Queue Model
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channel. In this model the channel processing unit is built that it doesn’t significantly
affect on the overall evaluation of the model performance.
Fig. 4.
OpenFlow switch conceptual model in AnyLogic 7.3.6
3.2
Packet Processing on the Controller
The controller manipulates multiple switches and therefore the arrival process of packets
at the switch characterizes the packet processing rate at the controller. Accordingly, the
model describes the packet transmission process management at different SDN model
service units. We consider SDN controller model as shown in Fig. 
5
.
Fig. 5.
SDN controller conceptual model in AnyLogic 7.3.6
Packet-in and Packet-out messages.
On the arrival of a packet, the switch checks the
flow table for presence of the destination address. The SDN model contains a central
unit (controller) manage flow entries in the network. In this model switch numbers match
the source and destination addresses. Forwarding rules and destination addresses for
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S. Muhizi et al.

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arrival packets are defined for each packets category arriving at the switch. First packet
of the category is sent to the controller for rules and destination address confirmation.
The controller determines the rule to assign to the respective packet category and sends
it back as a response to the packet-in message to the switch. The switch then forwards
the packet to the destination address. The next packets in this category then use the
assigned forwarding rules and there won’t be any requirement to confirm addresses. The
designed controller model works with a given failure rate. If the failure occurs, the entire
flow entry checking process starts again.