Finishing the Multisite Fabric
By now, you should be able to navigate through the multisite fabric hierarchy. If you haven't completed the DC1 or DC2 fabric setups, please do so before proceeding with the steps below.
Now, you are going to build the multisite fabric by combining DC1 and DC2. (Please note that you will not have the complete hierarchy until you finish the following steps).
Here's a helpful tip: To avoid any issues with the inter-DC links, ensure that all the inter-site links are up at this point. You can verify this by running a "show cdp neighbor" command to confirm that you are seeing the neighboring DC switches via the inter-site links.
Next, double-click the Multisite fabric name. This action will take you to the Fabric Overview menu.
Navigate to the Child Fabrics tab and click the Actions button. From there, select "Move Fabric into MSD" and choose Site-1 and Site-2 one by one.
Once you see the screen as shown above, select the "Recalculate and Deploy" action at the top Actions icon. If you have configured the multisite fabric correctly, all the necessary IP addresses, BGP settings, loopbacks, VTEP configurations, etc., will be generated, and you can safely deploy them to all the switches.
Wait for a while to allow the switches to deploy configurations and for the VTEP interfaces to come up. You should see that all multisite loopbacks are up when you go back to the Fabric Overview screen and scroll down.
Hurray! Now you have a functioning multisite EVPN-VXLAN fabric!
The next step involves configuring VLANs, interfaces, VRFs, IP routing, and more to make the network usable.
I won't delve into each step here since they are well-documented by Cisco. However, I will provide a couple of tips and guidance on where to configure them.
Configuring Interfaces: Regardless of the configuration snippet, pay attention when applying configurations to the multisite fabric:
When applying at the multisite fabric level, it means the configuration is applied across the entire fabric.
If you want to apply configurations at the per-site level, make sure to do so through the correct site's Fabric Overview menu.
Configuring interfaces is straightforward. Go to the Fabric Overview and locate the relevant interface, then use the Edit actions. You can always search for the required interfaces by using the "Filter by attributes" checkbox to narrow down your selection.
If you need to configure port-channels, vPC, SVIs (VLAN L3 interfaces), or FEX-type interfaces, use the Create action. Remember that in a typical NX-OS setup, creating a new interface is done through the Create action in NDFC.
Configuring VLAN: VLAN and the corresponding SVI configurations are done in the Networks tab within the Fabric Overview. This tab is named Networks because it associates VNI IDs with VLANs for cross-site purposes. NDFC utilizes the concept of networks to automate such configurations.
Once you've created the required network, you'll need to attach the network to the interfaces you've created earlier. Attachment is how NDFC tracks which VLANs and SVIs are associated with specific interfaces and whether the configurations have been deployed or not. Therefore, when attaching networks to switches, you'll be prompted to specify the interfaces as well.
Configuring VRF: Configuring VRF is similar to configuring Networks. You'll need to attach it to the required switches for it to take effect.
It's worth noting that NDFC uses the term "VRF-lite" for external routing connectivity. If you need to peer the fabric with external devices and configure related routing information, you can do so at the VRFs level through attachment.
Wrap Up
There are a lot of things you can explore with NDFC, such as setting up external BGP peering, introducing firewall pairs as service nodes, or creating a multisite network with 3 or even 4 sites (please note that the guide provided so far focuses on a setup with back-to-back BGW and only works for 2 sites). I'll save these advanced topics for future discussions when I have more time to delve into them.
Feel free to reach out if you encounter any challenges while building your lab. Good luck!
- End of Part 4 -
Gary Wong@Geelong, Australia. Nov 2023.
Comments