Since ACI release 3.1(1) it’s possible to use some Leaf Uplinks as Downlink Ports. This could help you out if there is a need for some 40/100G ports but you are currently only running 10/25G Leafs.
Currently, the following Leafs support the conversion:
- N9K-C93180YC-EX and N9K-C93180YC-EXU
- N9K-C9336C-FX2 (only downlink to uplink conversion supported)
There are some limitations, details can be found on the Cisco Page
Our use case was to use some of the 40/100G Uplink Ports as Downlinks on a N9K-C93180YC-FX. The main limitation there is that the last 2 ports (53 and 54) don’t support conversion, no issue if you use them as Uplinks anyway. Otherwise you have move first your Uplinks to 53/54 and then convert the ports to Downlinks.
The conversion process is pretty straight forward.
Head to Fabric -> Inventory, open up the respective POD and select your Leaf.
Go to the “Interface” tab and change the mode to “Configuration”
Now select the port you want to change from uplink to downlink and then select “Downlink”.
There will be a popup with the information about the change, “Submit” it.
And that’s it, repeat for all the other interfaces you want to convert. Then reload the Leaf.
After the switch is back up, you got the 40/100G Downlink ports ready to use.