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Network Routing and Queuing Disciplines Part 1 Analyze of Different Routing Protocols

The objective of the assignment is to configure and compare the performance of different Routing protocols with OPNET modeler.

Objective

The objective of the assignment is to configure and compare the performance of different Routing protocols with OPNET modeler.

Overview

A router in the network needs to be able to look at a packet’s destination address and then determine which of the output ports is the best choice to get the packet to that address. The router makes this decision by consulting a forwarding table. The fundamental problem of routing is: How do routers acquire the information in their forwarding tables? Routing algorithms are required to build the routing tables and hence forwarding tables. The basic problem of routing is to find the lowest-cost path between any two nodes, where the cost of a path equals the sum of the costs of all the edges that make up the path. Routing is achieved in most practical networks by running routing protocols among the nodes. The protocols provide a distributed, dynamic way to solve the problem of finding the lowest-cost path in the presence of link and node failures and changing edge costs. One of the main classes of routing algorithms is the distance-vector algorithm. Each node constructs a vector containing the distances (costs) to all other nodes and distributes that vector to its immediate neighbors. RIP is the canonical example of a routing protocol built on the distance-vector algorithm. Routers running RIP send their advertisements regularly (e.g., every 30 seconds). A router also sends an update

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message whenever a triggered update from another router causes it to change its routing table. OSPF is an interior gateway protocol that routes IP packets solely within a single routing domain (autonomous system). It gathers link state information from available routers and constructs a topology map of the network. The topology determines the routing decisions based solely on the destination IP address found in IP packets. OSPF detect changes in the topology, such as link failure, very quickly and converges on a new loop-free routing structure within seconds. It computes the shortest path tree for each route using a method based on Dijkstra’s algorithm, a shortest path first algorithm. In this lab, first you will set up a network and assign static routing and then utilizes RIP and OSPF as its routing protocol. You will analyze the routing tables generated in the routers, and you will observe how these algorithms are affected by link failures.

Procedure

Create a New Project in Campus scale and name the project _Routing, and the scenario Original. Make sure that Create Empty Scenario. Initializing the Network: 1. Add three ethernet4_slip8_gtwy from the palette to the project workspace. 2. Connect routers, using PPP_DS3 link model. 3. Connect two ehternet_wkstn objects to routers 1 and 2 by using duplex links of the form 100BaseT. 4. Add an ethernet_server and connect it to Router 3 by 100BaseT. 5. Make sure to set probable names to the nodes. (It is highly recommended to use the names shown in the picture.) 6. Save your project. At last you should have a similar topology as depicted in the following figure:

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Configuring the Application and Profile: 1. Add an Application Config and a Profile Config to your workspace. 2. Rename the configuration objects to Application and Profile respectively. 3. Define a new application. To do so, in the attribute of the application add a row and Name it Web with Http traffic and Page interarrival Time of exponen al (0.1). 4. In the attribute of Profile add a new profile with an arbitrary name. Select its application to be Web, operation mode to be Serial (Ordered), and the start time constant (100). 5. Set Users 1 and 2 to support your profile. 6. Set the Server to support your profile as well. Make sure to set the value of “Application: Supported Services” to All. 7. From the DES menu check the “Record Packet Flow 2D Animation For Subnet”. This will make the simulator store required data for visualizing the OPNET’s animation.

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8. Save the project.

Static Routing

In the first part, we are going to simulate static routing. Select Duplicate Scenario from the Scenario menu and name it Static.

Configuring IP Addresses: Work through this section carefully, and double-check your work. For assigning an IP address to the interfaces do the following for all the nodes: 1. In routers’ attributes Choose IP à IP Routing Parameters à Interface Information à Static Routing Table and enter the static routing table as demonstrated in the table. 2. In Stations and Servers’ attributes Choose IP à IP Host Parameters à Interface Information à Address as showed in the above picture. Note: When using static routing, it is the network administrator’s responsibility to keep monitoring and reconfiguring the network accordingly. Router 1 Rou ng Table Destination Subnet Mask Next Hop 192.0.6.1 255.255.255.0 192.0.4.1 192.0.2.1 255.255.255.0 192.0.3.1 Router 2 Rou ng Table Destination Subnet Mask Next Hop 192.0.6.1 255.255.255.0 192.0.5.1 192.0.1.1 255.255.255.0 192.0.3.2 Router 3 Rou ng Table Destination Subnet Mask Next Hop

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192.0.1.1 255.255.255.0 192.0.4.2 192.0.2.1 255.255.255.0 192.0.5.2 Routing Protocol Configuration: 1. Select ALL of the nodes in the network. 2. From the Protocols menu choose Protocols à IP à Routing à Configure Routing Protocols. 3. See Figure below:

4. In the dialog box select the desired routing protocol, or select None in the case of static routing. Uncheck the Apply selection to subinterfaces. In the “Apply the above selection to” section, make sure that you choose Interface across selected links. Finally, make sure Visualize routing domains is checked. Your network should look similar to this:

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To verify that our network is operating we will collect the following statistic:

• Right-click on the server and select Choose Individual DES Statistics and choose Node Statistics à TCP Connection à Load (bytes/sec). We are not interested in the load, but using this statistic allows us to see all the connections made to the server from workstations.

Configuring the Simulation: Run your scenario for 10 min. dura on. After running simulation for this scenario, select Play 2D Animation from the DES menu. A new window will appear (OPNET Animation Viewer) which enables you to view the animation output of the network. What happens if the link from Router 2 to Router 3 would fail? Disable the link between Router 2 and Router 3 (right-click on the link and select Fail This Link) and run the simulation again. What differences do you see in the results? Describe what should be done to overcome this situation?

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Routing Information Protocol (RIP)

Create a new scenario by duplicating the Original scenario, and name the new scenario RIP. Configuring the Routers: For all the routers in Edit Attributes → Reports → RIP Routing Table set the status value to Enabled and the export time to “Once at End of Simulation”. Routing Protocol Configuration: Make sure that you have selected RIP as the routing Protocol. (You can use the same steps as the last part.) Choose the Statistics: To test the performance of the RIP protocol, we will collect the following statistics: a. Global Statistics ⇒ RIP ⇒ Network Convergence Duration (sec) b. Global Statistics ⇒ RIP ⇒ Traffic Sent (bits/sec) c. Global Statistics ⇒ RIP ⇒ Traffic Received (bits/sec) d. Node Statistics ⇒ Route Table ⇒ Total Number of Updates Note: RIP traffic is the total amount of RIP update traffic in bits sent/received per second by all the nodes using RIP as the routing protocol in the IP interfaces in the node. Total number of updates is the number of times the routing table at this node gets updated (e.g. due to a new route addition, an existing route deletion, and/or a next hop update). Configure the Simulation:

1. Click on and the Configure Simulation window should appear. 2. Set the dura on to be 10.0 minutes. 3. On the left-side list, click on Inputs à Global Attributes tab and set the following attributes: a. IP Dynamic Routing Protocol = RIP. This sets the RIP protocol to be the routing protocol of all routers in the network. b. IP interface Addressing Mode = Auto Addressed/Export. Auto Addresses means that all IP interfaces are assigned IP addresses automatically during simulation. The class of addresses (A,B or C) is determined on the basis of the number of hosts in the designed network. Subnet masks assigned to these interfaces are the default subnet masks for that class. Export causes the auto-assigned IP interfaces to be exported to a file ip_address.gdf that gets saved in the primary model directory. c. RIP Sim Efficiency = Disabled. If this attributes is enabled, RIP will stop after the “RIP Stop Time”. But we need the RIP to keep updating the routing table in case there is any change in the network (as we will see in the following scenarios.)

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4. Click Apply and save the project.

Open Shortest Path First (OSPF)

Create a new scenario by duplicating the Original scenario, and name the new scenario OSPF. Configuring the Routers: For all the routers in Edit Attributes → Reports → OSPF Routing Table set the status value to Enabled and the export time to “Once at End of Simulation”. Routing Protocol Configuration: Make sure that you have selected RIP as the routing Protocol. (You can use the same steps as the First part.) Choose the Statistics: To test the performance of the OSPF protocol, we will collect the following statistics: a. Global Statistics ⇒ OSPF ⇒ Network Convergence Duration (sec) b. Global Statistics ⇒ OSPF ⇒ Traffic Sent (bits/sec) c. Global Statistics ⇒ OSPF ⇒ Traffic Received (bits/sec) d. Node Statistics ⇒ Route Table ⇒ Total Number of Updates Configure the Simulation:

1. Click on and the Configure Simulation window should appear. 2. Set the dura on to be 10.0 minutes. 3. On the left-side list, click on Inputs à Global Attributes tab and change the following attributes: a. IP Dynamic Routing Protocol = OSPF. b. IP interface Addressing Mode = Auto Addressed/Export. c. OSPF Sim Efficiency = Disabled 4. Click Apply and save the project.

Duplicate the Scenario (RIP)

In the network we just created, the routers will build their routing tables, and then they will not need to update them further because nothing in the topology of the network is going to change. In these scenarios we want to investigate the effect of link failure in routing tables of the routers. 1. Duplicate the RIP Scenario and name it RIP_Failure. 3. From the Utilities menu add a Failure Recovery node to your workspace and name it Failure. 5. Set the Failure’s node attribution so that “Campus Network.Router3Router2” would fail 200 seconds in the simulation.

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Duplicate the Scenario (OSPF)

Build a new scenario in which you fail the link between routers 2 and 3 again 200 seconds after the start of the simulation and name it OSPF_Failure. This time use OSPF protocol for this purpose.

Run the Simulation

To run the simulation for all of the scenarios simultaneously under the Scenarios menu, select Manage Scenarios. Here change the values under the Results column to (or ) for all of the scenarios.

View the Results

Compare the Number of Updates: 1. From the DES menu → expand the Results → Choose Compare Results. 2. Check the RIP and OSPF form le dialog box. 3. Change the drop-down menu in the right-lower part dialog box to Stacked Statistics. 4. Select the Total Number of Updates for Router 1 from the DES Graphs tab and click Show. 5. Two graphs will be shown a new window, one for each scenario. Right-click on each graph and change the Draw Style to Bar Chart. Obtain the IP Addresses of the Interface: Before checking the contents of the routing tables, we need to determine the IP address information for all interfaces in the current network. Recall that these IP addresses are assigned automatically during simulation, and we set the global attribute IP Interface Addressing Mode to export this information to a file. 1. From the File menu choose Manage Model Files → Refresh Model Directories. This makes OPNET to search the model directories and update its list of files. 2. From the File menu choose Open → From the drop-down menu choose “Generic Data File” → Select the _Routing-RIP-ip_addresses file (Also there should be similar file for other scenarios) → Click OK. 3. The opened gdf file should contain all the IP addresses and related interface between objects in our scenarios. Compare the Routing Tables Content: 1. To check the content of the rou ng tables in each router for all of the scenarios: From DES menu → expand the Results → Choose View Results → Choose the DES Run(1) Tables tab → expand the Object Tables → expand the Campus Network → Router1 (or any other router) → Performance → Routing Table – RIP at 600 seconds.

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2. Carry out the previous step for all of the scenarios and explain the tables.

Tasks

A. Describe the static routing by using snap shot from PacketFlow_anim. Answer the question stated at the end of that part. B. Obtain and analyze the graphs that compare the sent RIP traffic for RIP and RIP_Failure scenarios. Make sure to change the draw style for the graphs to Bar. C. Repeat the previous task for scenarios OSPF and OSPF_Failure. D. Obtain and analyze the graphs that compare the Network Convergence Duration for all of the scenarios for Router 3. E. Obtain and analyze the graphs that compare the Total Number of Updates for all of the scenarios for Router 3. F. Obtain the assigned IP addresses and interfaces for the whole network. Also discuss the definition of Subnet Mask. G. Describe and explain the effect of the failure of the link connecting Router 2 to Router 3 on the Routing Tables of the routers. H. Describe and explain the effect of the failure of the link connecting Router 2 to Router 3 on the Traffic Received by User 2. You should explain the difference between RIP and OSPF. I. Create another scenario as a duplicate of the RIP_Failure scenario. Name the new scenario RIP_Recover. In this new scenario have the link connecting Router 2 to Router 3 recover a er 400 seconds. Generate and analyze the graph that shows the effect of this recovery on the Total Number of Updates in the routing table of Router 3. Check the contents of the Router 3’s routing table. Compare this table with the corresponding routing tables generated in the RIP and RIP_Failure scenarios. J. Describe and explain the situation in scenario PacketFlow_anim. Use proper snapshots from the animator to prove your statement.

Part 2 Quality of Service: Impact of Queuing Policy

Order of Packet Transmission and Dropping

Objective

The objective of this part is to examine the effect of different queuing disciplines on packet delivery and delay.

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Overview

In a store-and-forward network, routers maintain one or more queues for each output line. These are necessary as a packet may arrive and be destined for a line which is already busy. A queuing policy defines a set of rules for placing packets into the queue and taking them back out. The traditional policy is First-In, First-Out (FIFO), which is easy to implement and treats all data streams the same. A packet which has newly arrived is placed at the end of the queue and waits its turn to be sent. Now that the Internet is also used to carry voice and video streams, simple FIFO mechanisms are not sufficient. Voice and video applications require bounds on the delay and delay variation (jitter) that a packet will experience. One way to implement these bounds is to treat the packets differently within the router’s queues. In the Weighted Fair Queuing (WFQ) policy, one queue is maintained for each priority class. Weights are associated with the classes based on their importance. Queues are then serviced (i.e., packets are taken from the queues and sent on the outgoing line) at rates based on their weights. For instance, if queue A was assigned a weight of one, and queue B was assigned a weight of two, then two packets would be sent from queue B for every one sent from queue A. By assigning voice and video streams to a queue with higher weight, they can be given precedence over standard data traffic. In the Priority Queuing policy, multiple queues are again maintained based on the priority classes assigned to the packets. In this case though, all high-priority packets get sent before any low-priority packets. If we have two queues, one configured to handle priority-one traffic, and one configured to handle priority-two traffic, the priority-two queue will be serviced until it is empty, and only then will the priority-one queue be serviced. Priority one transmissions will be preempted if any new priority-two packets arrive

Procedure

Create a New Project:

1. Start OPNET ⇒ Choose New from the File menu. 2. Select Project and click OK ⇒ Name the project _QoS_Queuing, and the scenario PQ ⇒ Click OK. 3. In the Startup Wizard: Initial Topology dialog box, make sure that Create Empty Scenario is selected ⇒ Click Next ⇒ Select Campus from the Network Scale list ⇒ Click Next three times ⇒ Click OK Initialize the Network:

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1. The Object Palette dialog box should be now on the top of your project space. If it is

not there, open it by . Make sure that the internet_toolbox item is selected from the pull-down menu on the object palette. 2. Add to the project workspace the following objects from the palette: Application Config, Profile Config, two ppp_wkstn, one ppp_server, and two ethernet4_slip8_gtwy routers. 3. Connect server to the routers with a duplex PPP_DS3 link. 4. Connect the worksta ons to the routers, and two routers together using duplex PPP_DS1 links as shown. 5. Rename the objects you added as shown and then save your project.

Configure the Applications: 1. Right-click on the Applications node ⇒ Edit Attributes ⇒ Expand the Application Definitions hierarchy ⇒ Set rows to 2 ⇒ Name the rows: FTP_Low_Priority_Application and FTP_High_Priority_Application. i. Go to the FTP_Low_Priority_Application row ⇒ Expand the Description hierarchy ⇒ edit the value of the Ftp attribute ⇒ set the Inter-Request Time (secs) attribute to exponen al(5) ⇒ Assign Constant(500000) to File Size (bytes) ⇒ Keep the Type of Service (ToS) as Best Effort (0)

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à Type of Service (ToS) is assigned to the IP packets. It represents a session attribute that allows packets to be provided the appropriate service in the IP queues à Best-effort delivery means that delivery of a packet is attempted but is not guaranteed à FTP = File Transfer Protocol ii. Go to the FTP_High_Priority_Application row ⇒ Expand the Description hierarchy ⇒ edit the value of the Ftp attribute ⇒ set the Inter-Request Time (secs) attribute to exponen al(5) ⇒ Assign Constant(500000) to File Size (bytes). ⇒ Change the Type of Service (ToS) to Excellent Effort (3).

2. Click OK and then save your project. Configure the Profiles: 1. Right-click on the Profiles node ⇒ Edit Attributes ⇒ Expand the Profile Configuration hierarchy ⇒ Set rows to 2. i. Name and set the a ributes of row 0 as shown:

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ii. Name and set the a ributes of row 1 as shown:

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2. Click OK and then save your project. Configure the Clients and Server: 1. Right-click on the FTP Low Client node ⇒ Edit Attributes ⇒ Expand the Application hierarchy ⇒ Edit the Application:Supported Profiles attribute ⇒ Set the rows attribute to 1, and set the Profile Name to FTP_Low_Priority_Profile ⇒ Click OK to close the window. 2. Right-click on the FTP High Client node ⇒ Edit Attributes ⇒ Expand the Application hierarchy ⇒ Edit the Application:Supported Profiles attribute ⇒ Set the rows attribute to 1, and set the Profile Name to FTP_High_Priority_Profile ⇒ Click OK to close the window. 3. Right-click on the FTP Server node ⇒ Edit Attributes ⇒ Expand the Application hierarchy ⇒ Edit the Application:Supported Services attribute ⇒ Set the rows attribute to 2 ⇒ Set the Name in the first row to FTP_Low_Priority_Application ⇒ Set the Name in the second row to FTP_High_Priority_Application ⇒ Click OK to close the window. 4. Save the project.

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Configure the Routers: 1. Right-click on the QoS Router node ⇒ Choose Select Similar Nodes ⇒ Select the Protocols tab ⇒ IP ⇒ QoS ⇒ Configure QoS… ⇒ set the QoS Scheme to Priority Queuing. 2. Click on the radio bu on next to Interfaces on selected router(s) and make sure the selected items are as shown in the following QoS Configuration dialog box ⇒ Click OK.

You have now configured the QoS router to use priority queuing mechanism on its interfaces. Note that a Qos Config object automatically appears in the project workspace this is done due the fact that we configured the QoS Router to use queuing mechanisms. Right click on the PPP link that connects Qos Router and Router 1, and choose Edit Attributes. Inspect the transmitter and receiver a and b attributes to see which interface is being used on the QoS Router (IF10 in our example). Your configura on may differ from the one shown, depending on how you placed your PPP link. Click OK to close the window.

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3. Right-click on the QoS Router node ⇒ Choose Edit Attribute ⇒ Expand the IP ⇒ IP QoS Parameters ⇒ Interface Information ⇒ and the row item for the interface you just found, IF10 in our example ⇒ Edit the Buffer Size (Bytes) attribute to 100000. Click OK to close the window. By making the buffer size on this interface relatively small, buffer overflow will occur more quickly, allowing us to see the results of the different queuing mechanisms more easily. Note that overflow would eventually occur anyway since the FTP Server is genera ng lots of traffic over DS3 line which connects it to QoS router, but the QoS router has only DS1 line to forward traffic on the clients. 4. Save your project.

Choose the Statistics

1. Right click on the QoS Router and select the Choose Individual Statistics. Expand the IP Interface item, and select the Buffer Usage (packets), the Queue Delay Variation (sec), the Queuing Delay (sec), and the Traffic Dropped (packets/sec) statistics.

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2. Click OK and then save your project Configure the Simulation: Here we need to configure the duration of the simulation:

1. Click on and the Configure Simulation window should appear. 2. Set the dura on to be 20 minute(s). 3. Click Run.

Duplicate the Scenario

1. Duplicate your scenario and name it WFQ (for Weighted Fair Queuing). Select both routers and choose the Protocols tab ⇒ IP ⇒ QoS ⇒ Configure QoS…⇒ Set the QoS Scheme to WFQ ⇒ Click on the radio button next to Interfaces on selected router(s). Click on OK to close the window. Rerun the simulation and examine the relative packet drop rate, delay, delay variation, and buffer occupancy. Explain your results. 2. Duplicate your scenario and name it FIFO. ⇒ Select the two routers and choose the Protocols tab ⇒ IP ⇒ QoS ⇒ Configure QoS… ⇒ Set the QoS Scheme to FIFO. Click on the radio button next to Interfaces on selected router(s). Click on OK to close the window. Rerun the simulation and examine the relative packet drop rate, delay, delay variation, and buffer occupancy. Explain your results.

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Run the Simulation

To run the simulation for the three scenarios simultaneously: 1. Go to the Scenarios menu ⇒ Select Manage Scenarios. 2. Change the values under the Results column to (or ) for the three scenarios. 3. Click OK to run the three simulations. Depending on the speed of your processor, this may take several minutes to complete. 4. A er the simula on completes the three runs, one for each scenario, click Close. 5. Save your project.

Questions

1. Compare the Weighted Fair Queuing, Priority Queuing, and FIFO schemes in terms of drop rate, delay, and delay variation. What are the advantages and disadvantages of each? 2. Edit the a ributes of the QoS Parameters object. Look in the WFQ Profiles a ribute at the ToS based profile. What weights are associated with the various ToS values in the WFQ scheme? How do these weights affect the operation of the router? 3. Edit the a ributes of the QoS Parameters object. Look in the Priority Queuing Profiles at the ToS based profile. How many priority levels are defined? What ToS values are associated with each priority level? 4. Edit the a ributes of the QoS Parameters object. Look in both the Priority Queuing Profiles and the WFQ Profiles. Other than ToS, how else may packets be classified for priority service?

Experiment Report

Write a proper report using MS Word and include the results and discussions of your results in the report. You should then pack this report with the project file in your OPNET (The project Name should be the same as your name_LAB4), zip them and upload it in the cw. The received file should contain: The OPNET project The answers to the above questions and tasks The results of simulations in the form of OPNET Plots (Directly Print screened or exported to another form). For each part, explain the results you have found and how they are related to the theories discussed in the course.