Difference between even and odd ports on N9K-C93180LC-EX

[Christoph Neulinger]

Hi colleagues,

I discovered a strange behavior on the N9K-C93180LC-EX switches in our Test environment.

I needed to connect 2 DELL servers to the ACI Leaves. The servers have two Dual NIC cards (Intel(R) Ethernet 25G 2P XXV710 Adapter) installed. We use a QSFP to SFP adapter and a 5m DAC (SFP-H25GB-CU5M) cable for connection. I connected the servers on both switches of an vPC pair on the same ports (eth1/9 - eth1/12). Only half of the ports, the odd numbered where afterwards in the up state (eth1/9 and eth1/11).

We tested swapping ports on the switch side and it where the same port on the switch site that didn't come up. Selecting another port on the switch (et1/13), the port came up. Selecting another odd port (eth1/20), the port didn't come up.

On all ports even and odd the transceiver type was correctly discovered. The operational state reason was link-failure on the ports not coming up.

As this is happening on 2 switches and it's the exact same behavior I exclude and hardware failure.

Is there anything different on the even and odd ports?
Anyone else seen this behavior?

Kind regards

Christoph

[Sergiu.Daniluk]

As far as it looks like in the Optics Compatibility matrix: https://tmgmatrix.cisco.com/?si=N9K-C93180LC-EX

SFP-H25GB-CU5M twinax is not supported by this platform.

Cheers,

Sergiu

[Christoph Neulinger]

@Sergiu.Daniluk 
thanks I get that but why is it working on the odd ports?

I would understand if it's working on none of the ports but this way it seems very strange to me.

I wasn't aware that there is a difference between even and odd ports on this switch.

Cheers Christoph

[Sergiu.Daniluk]

Maybe that is the actual reason why SFP-H25GB-CU5M is not supported - only the odd ports come up.

To answer your initial question, I am also not aware of difference between odd and even ports.

Stay safe,

Sergiu

[Robert Burns]

Certain platforms leverage different ASICs with different capabilities.  On the 93180LC-EX, only odd ports are supported for Breakout (1 through 24).  When Odd ports are broken out, the lower (even) port will be disabled.  As Sergiu pointed out, the TMG matrix is your first stop.  Second stop is the ACI L2 Config Guide to ensure ACI supports the optics & breakout options.    

Robert