Design Project:



1) the link delay histogram for any 2 links you choose and average delay

2) The histogram for the link flows for 2 other links you choose and each average

3) Determine Ave end to end delay and ave number of hops for this network


1) the routing used (whether min number of hops or others)

2) the channel capacity to be used ( link utilization ≤ 0.5)





Assume MEAN Packet size = 800 bits per packet



To design a network where all the link utilization is less or equal than 0.5, we have to get the utilization of the network selecting first the routing protocol and all the link demands.

Once we have the utilization for every link, we can choose the link capacity that satisfies the requirements.


For this network, all the nodes are routers of the kind ethernet4_slip8_gtwy. Each of them have 4 Ethernet ports and 8 serial ports. Each port utilized in the network was assigned an IP address according to the subnet were it was operating.

The routing protocol configured in the network was the RIP protocol. For the preliminary tests, all the links were 10BaseT.

The traffic between links were configured using the ip_traffic_flow from the "Demands Models" included in the OPNET library. Each of them was configured with the respective traffic specified on the table shown in the previous page with an exponential packet size PDF and exponential packet inter-arrival time PDF.


The Network Design is shown in the pictures below.


Picture 1 - Network without the IP demands.


Picture 2- The network after the IP Demands were applied.



Picture 3 IP Configuration



To be sure that the dimensioning of the links was correct, a link utilization reports was generated, and the results below show that the link utilization is below 50%, and at the same the links are not over dimensioned. The results show a maximum utilization of 0.5%, which is because the traffic in the network is extremely low.

Picture 4 Physical Link utilization



The link delay histogram and average delay was analyzed on the links A-C and B-G.


Link A-C


Link Delay Histogram for link A-C




Average Link Delay Histogram on link A-C

Average packet delay on link A-C





Average packet delay on link C-A


Link B-G


Link Delay Histogram for link B-G




Average Link Delay Histogram on link B-G


Obs: The difference between the delay on traffic going from B to G and the traffic going from G to B is due to the Routing protocol selected. When a dynamic routing protocol is configured (in this case RIP), each router will select the route to destination according to his point of view of the network. This makes the traffic in a physical link different in both directions. An example of this is shown in the Annex 1.


Average packet delay on link B-G





Average packet delay on link G-B



The histogram for the link flows and the average were analyzed on the links A-D and E-F


Link A-D


Link flow on link A-D




Average link average on link A-D


Link E-F


Link flow on link E-F




Average link average on link E-F

3)     Average end to end delay and average number of hops for the network



Average end to end Delay



Average number of hops

Annex 1


Routing table for router E



Routing table for router F



Different routes followed in opposite direction.

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