Applicable VersionsNetSim AcademicNetSim Standard


Applicable Releasesv13 and above


Processing/computing delay is available as a GUI parameter from v13 onwards. You can find the Processing Delay parameter by Right Clicking on the Device – Properties – Network Layer – Processing Delay (µs).

 
This property is available in all Layer 3 devices but is not present in L2-Switch and Access-Point devices. Thus, processing delay can be set at source nodes, destination nodes, or at intermediate devices.



Example Scenario


Given below is a simple IoT network configured with an HTTP application between the client and server


  • HTTP Application Properties configured such as Page Size (B) set to 100 B and Page Count is 1 and HTTP Request Inter Arrival Time set to 1 sec as shown below. 


  • We configure the processing delay in Server Node Properties – Network Layer – Processing Delay (µs) as 10000 µs. 


  • Enable the Packet Trace and from GUI as shown below


  • Run the Simulation for 100 sec.


Processing delay measurement in the trace file
Open the packet trace by clicking on packet trace from the results dashboard.
To observe the processing delay, please follow the steps outlined below.


1.     Filter the CONTROL_PACKET_TYPE to data packets (APP1_HTTP)
2. Also filter the Transmitter ID to Node 4 as the Processing Delay is introduced at that particular node.

3. Insert a new Column and Calculate the Processing Delay by taking the difference between MAC LAYER ARRIVAL TIME(µS) and NW LAYER ARRIVAL TIME(µS)
            Processing Delay = MAC LAYER ARRIVAL TIME(µS) - NW LAYER ARRIVAL TIME(µS)

Results without Processing Delay: In the results window observe the Delay(µs) in the Application metric window. This is the case with the processing delay set to 0.0 microseconds.


In the above figure of an HTTP application, there are two distinct communication flows. Firstly, the client, identified by Source ID 1, initiates a request that is transmitted to the server with Destination ID 4. Next, the server generates a response to the client's request, which is sent back from the server with Source ID 4 to the client with Destination ID 1.


Results with Processing Delay: In the results window observe the Delay(µs) in the application metrics window. This is the case with the processing delay set to 10000 µs. The delay value in application metrics is an End to End Delay, however, End to End Delay is calculated as the addition of Actual Delay (µs) and Propagation Delay (µs).


You can observe in the previous simulation where the Processing delay is 0.0 we get an end-to-end delay of 5902.78 µs and now you can observe that in addition to that, 10000 µs of (processing) delay has been added to the end-to-end delay.



Part B: Example use case - Modeling Processing Delay in an IoT network running RPL routing protocol


Create a network with multiple sensors and one server. We have configured one HTTP application as shown below



We have set the Routing Protocol to RPL in Sensor Device -- Properties -- Network Layer as shown below

We have configured the HTTP Application Between the Client and Server with properties such as Page Size (B) set to 100 B and Page Count is 1 and HTTP Request Inter Arrival Time set to 1 sec and Random Startup set to TRUE as shown below. 


Effect of Processing Delay
Now we can observe the effect of Processing Delay by changing the Processing Delay parameter

Processing Delay (µs)Delay (µs) HTTP REQUESTDelay (µs) HTTP RESPONSE
0.018332.1118816.56
50018332.1119316.56
100018332.11
19816.56
5000
18332.11
23816.56
1000018332.11
28816.56
5000018332.1168816.56
10000018332.11
118976.56

The REQUEST packet is generated from Client to Server, while the RESPONSE packet is generated from Server to Client. As we increase the processing delay in the server we observe an equivalent increase in the HTTP response time from the server.

Useful links


1. NetSim IoT overview: https://www.tetcos.com/iot-wsn.html

2.  Users interested in visualizing the RPL DODAG can see How to visualize the RPL DoDAG formed in NetSim IoT network? : NetSim Support Portal (tetcos.com)