SD Access Network migration from traditional network

[Sefik]

Hi,

I have an upcoming installation and i want to clear some doubts. Customer's existing network is a traditional Core-Dist-Access network. All links are layer 2 and trunk between devices. You can see it below

9500(Core)-------L2Trunk------9500(Dist)------L2Trunk-----9200(Access)

There is a vlan for management and for every switch there is a management ip address which assigned under management vlan interface. I know i can discover all devices using DNA and then push configuration. But as you know before implementing sd access we need to construct layer 3 underlay. And for this layer 3 underlay to work, all connections between our switchs should be point to point layer 3 links. It is better to use /30 networks between switches and also provide a /32 loopback ip address for every switch for VXLAN tunnels. My question is;

How this works? After I discover all my switches I will create a fabric. And then I will assign roles for my switches. 9500(Core) will be marked as Border and Control and 9200 will be marked as Edge. But how about the layer 3 point to point links between switches and ip addresses for loopbacks? I will add them in DNA as layer 2. Does dnac push also layer 3 configuration and loopback addresses to devices when i assign them their roles in fabric ? Because we are not saying anything about the distribution switch. This is a migration from traditional network to SD access and I wonder if i need to configure layer 3 links and ISIS(Or OSPF) manually before I add them to my fabric?

I read the migration guide but it is not mentioning about this part. Guide only shows that I should add my devices and then assign their roles. As far as I know when you enable fabric and assign roles to devices, DNAC only pushes configuration about LISP to Border and Edge nodes. My understanding is underlay must be there before this happens. 

And if DNAC cannot push point to point link  and loopback configuration, how should i proceed? Manual configuration of underlay?

Customer has a running network so Lan Automation Tool is not an option.

Thanks. 

[Dan Rowe · Accepted solution]

Hello,

Try and refer to your P2P links between your network devices as your underlay. DNAC does have the ability to automate this configuration through LAN automation in which DNAC will configure the P2P links for ISIS and a Loopback 0 interface however you are not required to use LAN automation. In other words, you can manually configure your underlay and DNAC will accept this. When you provision your network devices to your fabric as border nodes or edge nodes, DNAC will essentially provision overlay configuration (LISP, VRFs, etc) only.

If LAN automation is not an option, then you will need to manually configure your underlay or you can also use a configuration template on DNAC to push the configuration down to the network devices.

Best Regards,