Version 11 (modified by, 4 years ago) (diff)


A Tutorial on Systematic Experimental Design

Step I: Single Node

Step II: Small Topology

Image Map

1. Software Configuration

Once we have installed the software on the VM, we may need to configure the software, and automate the configuration process for every node used in an experiment. For this tutorial, since we are setting a virtual routing environment, we will need to configure the routing protocol (e.g., OSPF protocol) for Quagga. Again, let's start with the smallest reasonable topology, which is a four-router virtual topology as shown below. The reason that we chose the four-router topology is that we need at least one pair of routers that are not directly connected to each other and each router must have at least two virtual interfaces.

a. Create Virtual Network

As we have mentioned, a four-router topology is the smallest topology to configure and verify the OSPF routing. In this part, we illustrate how to create a virtual network with four virtual routers.

Create four VMs from the same InstaGENI aggregate and add the links. Modify each VM's name, set the Sliver Type to emulab-xen, and load the custom image by following the steps in the Verify Custom Image section. You may use the the value in the Disk Image option for each router in this topology.

The network configuration address assignment is given below:

 router-1 (.1) <-----> router-2 (.2) on
 router-2 (.1) <-----> router-3 (.2) on
 router-3 (.1) <-----> router-4 (.2) on
 router-4 (.1) <-----> router-1 (.2) on
 router-2 (.1) <-----> router-4 (.2) on

ii. Configure Virtual Interfaces

Configure the virtual interfaces' IP addresses of each link as outlined in the network configuration address assignment list above:

(1) Click on the link to be configured
(2) Enter Address for one interface
(3) Scroll down and enter address for the other interface part of the link.
(4) Repeat for each of the list shown in the network configuration address assignment list.

iii. Delete Routes installed by InstaGENI

To overcome the issues faced in topologies with loops due to the way routes are installed in InstaGENI, we need to delete those routes on each node. This can be done by turning off and then turning on all the interfaces on a node except eth0 . The script to do this task can be found at .

(1) Click on the node to be configured
(2) Scroll down till you see Install Tarball and click on Add.
(3) Enter the url Enter /local as the Install Path.
(4) Scroll down till you see Execute Command and click on Add. Enter sh /local/ in the box.

iv. Disable RP Filtering

Reverse Path Filtering is enabled by default in Linux. This creates issues for topologies with loops. Hence we have to disable Reverse Path Filtering on all interfaces except eth0 . The script to turn off Reverse Path Filtering can be found at .

1) Click on the node to be configured
(2) Scroll down till you see Install Tarball and click on Add.
(3) Enter the url Enter /local as the Install Path.
(4) Scroll down till you see Execute Command and click on Add. Enter sh /local/ in the box.

v. Save the Current RSpec

For version control purposes, it is important to save the resource request specification (RSpec) at each step. Thus, once we have defined the topology above, we select the Download button to save an intermediate version of your RSpec.

Note The download command does not allow naming it simply uses the slice name to generate a RSpec file. We have save a copy of this RSpec, which you may choose to download, available at here

You may now reserve your resources by scrolling to the bottom of the Add Resources page ans clicking on the Reserve Resources button:

b. Manually Configure OSPF for Quagga

In this tutorial we configure each VM as a virtual router running the OSPF routing protocol. The commands used for configuring OSPF can be found at

To configure OSPF on router 1, do the following steps:

pjayant@router-1:~$ sudo su
root@router-1:/users/pjayant# vtysh

Hello, this is Quagga (version
Copyright 1996-2005 Kunihiro Ishiguro, et al. conf t router ospf network area 0 network area 0

Similarly on routers 2,3 & 4; configure OSPF by following the above steps and adding networks,,, & to area 0.

c. Verify Routing

View the OSPF routing table on router 1: do sh ip ospf  route  
============ OSPF network routing table ============
N        [10] area:
                           directly attached to eth3
N        [20] area:
                           via, eth3
N        [20] area:
                           via, eth1
N        [10] area:
                           directly attached to eth1
N        [20] area:
                           via, eth3
                           via, eth1

============ OSPF router routing table =============

View the OSPF routing table on router-3: do sh ip ospf  route  
============ OSPF network routing table ============
N        [20] area:
                           via, eth2
N        [10] area:
                           directly attached to eth2
N        [10] area:
                           directly attached to eth3
N        [20] area:
                           via, eth3
N        [20] area:
                           via, eth2
                           via, eth3

Since router-1 and router-3 are not directly connected, by OSPF routing, we should be able to run ping and traceroute between them. do ping
PING ( 56(84) bytes of data.
64 bytes from icmp_seq=1 ttl=63 time=2.03 ms
64 bytes from icmp_seq=2 ttl=63 time=1.86 ms
64 bytes from icmp_seq=3 ttl=63 time=1.72 ms
--- ping statistics ---
3 packets transmitted, 3 received, 0% packet loss, time 2002ms
rtt min/avg/max/mdev = 1.722/1.871/2.031/0.131 ms do traceroute
traceroute to (, 30 hops max, 60 byte packets
 1  router-2-link-1 (  1.161 ms  1.117 ms  1.042 ms
 2  router-1-link-0 (  2.213 ms  2.161 ms  2.101 ms

2. Add End Hosts and Install iperf

Once we have verified the routing functions for the virtual router, we add end hosts to validate the end-to-end communication. As the figure shows below, we create the same four-node topology by loading Quagga_4node_rspec.xml on the GENI Portal and create two more VMs as a client and a server, and add two virtual links. The links between end-hosts and edge routers are configured as below:

client ----- router-1:
server ----- router-3:

For client and server, follow the same steps as we followed in the Verify InstaGENI Custom Image section. We also need to delete any routes installed by InstaGENI. Follow the steps followed in section iii of Create a Virtual Network. Also we need to install iperf separately. In this example, there are only two hosts which need iperf installed, so one option is to login to each host, and manually install it by running

sudo apt-get install iperf

Or, we can also write a script to install iperf to the client and server, load it as an install script. The install scripts for client and server can be downloaded from here. An sample RSpec with iperf install script and execute command can be downloaded at `4node-v4.rspec`.

SAVE the new RSpec to 4node-v4.rspec, when all nodes have been reserved.

Small Topology: Introduction

Small Topology: Execute

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