Nexus 9300 Uplink Port Limitations & Requirements

[CNM88]

I'm struggling to remember where I saw this but I believe I read that the "uplink" 40/100Gb ports on the 9300-EX switches can only be used as uplink ports to upstream switches and not to any host-level or VPC connectivity. Maybe I'm dreaming this. Side note: this is in regards to NXOS mode and not ACI. Perhaps what I'm thinking of was ACI-specific. Can anyone confirm if this is a true limitation or not. 

[james.kazin]

It's not that the ALE ports can't be used for non-uplink roles in NX-OS (I've done it in isolated lab environments), but due to some of the platform limitations, they probably shouldn't be.

For ACI mode, the ALE ports are fabric spine link ONLY.

http://www.cisco.com/c/en/us/td/docs/switches/datacenter/nexus9000/sw/ale_ports/b_Limitations_for_ALE_Uplink_Ports_on_Cisco_Nexus_9000_Series_Switches.html

[TimMiller]

Caveat - each model can have its own specific limitations, so you should always check each model specifically.

That being said, generally, for the 9300-EX and 9300-FX models, in stand-alone NX-OS mode, the "uplink ports" can be used for VPC and end-host connectivity.

In the first generation 9300s, however, the uplinks are connected to an ALE ASIC whose primary use case is ACI spine uplinks.  So, in standalone NX-OS mode, those ports have quite a few limitations, documented here:

https://www.cisco.com/c/en/us/td/docs/switches/datacenter/nexus9000/sw/ale_ports/b_Limitations_for_ALE_Uplink_Ports_on_Cisco_Nexus_9000_Series_Switches.html

With regards, currently (ACI 3.0(1) and earlier), the uplinks on Nexus 9Ks are restricted to spine uplinks and not supported for "downlink" usage.

[Robert Parten]

Sorry to respond to such an old post; however, an important difference between the Cisco Nexus 9300 and the 9300-EX/FX must be explained here, which also answers the original posters question.

The Cisco Nexus 9300 (first generation like the 9396PX and 9372PX) use an Application Leaf Engine (ALE) ASIC. The second generation of Cisco Nexus switches (as in the referenced Cisco Nexus 93180) utilize a Leaf-and-Spine Engine (LSE) ASIC which DOES NOT have the same limitations as the ALE ASICs in the first generation Nexus 9K switches.

However, there are still limitations and caveats for the uplink ports on the LSE based, second generation 9300-EX/FX switches which should be verified against the guidelines/limitations documentation for either the NX-OS operating mode or the Cisco ACI operating mode.

At least for NX-OS operating mode, you can use the 40GbE uplinks for vPC peer-link, end-host connectivity, and for FEX 40GbE uplinks, which wasn't possible with the first generation Cisco Nexus 9K switches that used the ALE ASICs