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We've prepared a simple emulated Mininet topology, which contains 6 OpenFlow switches. Connected around the edges of the SDN network are 4 emulated routers. The routers run Quagga, which is an open-source routing suite. In our case we run the BGP part of Quagga on them, to simulate external BGP routers belonging to other administrative domains. The goal of SDN-IP is to be able to talk BGP with these routers in order to exchange traffic between the different external ASes.

 

This figure shows the topology as observed by ONOS. We can see 6 blue OpenFlow switches, and 5 hosts around the edge.

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Code Block
mininet> h1 ping h2
PING 192.168.2.1 (192.168.2.1) 56(84) bytes of data.
64 bytes from 192.168.2.1: icmp_seq=1 ttl=62 time=0.693 ms
64 bytes from 192.168.2.1: icmp_seq=2 ttl=62 time=0.139 ms
64 bytes from 192.168.2.1: icmp_seq=3 ttl=62 time=0.149 ms

The ping succeeds! 

Advertising a new route

Now that we've got a the system up and running, let's see what happens when there's a change in the BGP routes. We're going to make one of the external routers advertise a new route, which will allow us to talk to a new host. Right now r4 is not advertising any routes, and so we can't talk to h4. Let's verify this by trying to ping h4.

Code Block
mininet> h1 ping h4
PING 192.168.4.1 (192.168.4.1) 56(84) bytes of data.
From 192.168.1.254 icmp_seq=1 Destination Net Unreachable
From 192.168.1.254 icmp_seq=2 Destination Net Unreachable
From 192.168.1.254 icmp_seq=3 Destination Net Unreachable
From 192.168.1.254 icmp_seq=4 Destination Net Unreachable

Yep, looks like we can't reach h4 yet.

To make r4 advertise a new route, we have to change the configuration of the BGP router. In our case, the BGP router is a Quagga process, so we'll connect to the Quagga CLI and configure r4 to advertise a new route. (The Quagga CLI is complex and includes lots of options, but considering this is not a Quagga tutorial we don't have the time to explain too much about Quagga. If you're interested, there's material online that will help you understand Quagga).

First, from Mininet we can start up an xterm so we can connect to the Quagga CLI.

Code Block
mininet> xterm r4

A little xterm window will pop up. The next few commands will by typed into this xterm window.

Image Added

We can use telnet to connect to the Quagga CLI.

Code Block
root@ubuntu:~# telnet localhost 2605
Trying 127.0.0.1...
Connected to localhost.
Escape character is '^]'.
Hello, this is Quagga (version 0.99.23).
Copyright 1996-2005 Kunihiro Ishiguro, et al.

User Access Verification
Password: 

It will prompt for a password, which is sdnip. Once the password is entered, we'll drop into a prompt {{r4> }}.