In our VIRL machine, we will utilize the two flat networks presented by default. We have been using the flat network connected to VMNet2 on 172.16.1.0/24 as the management network. We will connect a third virtual Ethernet interface to VMnet3 on 172.16.2.0/24:

In our scenario, we will leave the management network as private project network (which we can still use to ssh to), as our link to the Mininet topology to simulate leaf-2 while using flat-1 as the control plane BGP peer to our Ryu BGP speaker.

It may seem like an overkill to have two separate controller applications, one for BGP peer and the other for router. The reason for performing the migration this way is because I believe it is useful to see that the two functions can be de-coupled, which is many times not the case for vendor-purchased equipment. Having two separate applications can also be more scalable down the line, if you want to keep adding ToR routers without needing to spin up a new BGP speaker. Finally, we have already worked with the BGP speaker application as well as the router application in Chapter 11, OpenFlow Advance Topics. By using the same tool, we can build on what we already know.

Now that we have the lab ready, let's take a look at the configuration we are started with.