SFP-10/25G-CSR-S to SFP-10G-SR

[MichalD]

I'm trying to connect a Nexus c93240yc-fx2 using the 10/25G-CSR-S sfp to a 3850 using the 10G-SR sfp. I can't get the link to come up no matter what speed settings I put on either side. When I use another 10G-SR on the Nexus side, the link comes up no problem. I also find it surprising that the 10/25G-CSR-S shows up as type SFP-H25HB-SR when i run the show int status and show int trans commands on the NX. Any ideas or experiences on this matter? Thanks! 

[Leo Laohoo]

What firmware is the 3850 running on?

[MichalD]

The 3850 is running 3.7.3E. I double checked the Compatibility Matrix and found out that 10/25-CSR-S requires minimum NXOS release of 9.2.1 and I'm running 7.0(3)I7(5) on the C93240YC. To test it further I used those SFPs to connect two 93240YCs and the link came up only at 25G. When I forced both sides to 10G, as suspected, the link remained down. I have some regular 25-SR SFPs as well and the NXOS recognizes both the 10/25G and 25G as type SFP-H25GB-SR, which would further point to the incompatible code.

[Leo Laohoo]

3850 won't support SFP-10/25G-CSR-S. Ever.
SFP-10/25G-CSR-S is supported in the Catalyst 9200/9300/9400/9500/9600.

[MichalD]

Right, I am using 10/25-CSR on the 9k but could not get it to run at 10G with 10G-SR in the 3850 on the other side of the link.

[ohgrowup2001]

Hello....Just wondering if there is any confirmation what you are seeing. I have the following running

n9000-13.2(5d)
N9K-C93180YC-EX

showing the same incorrect SFP.

Is this the standard output for incompatible code, to give an incorrect part number? It's a very odd display, as the port shows as operational at 25G. I am only trying to use the interface as a 10Gig connection and had initially thought that the issue was the far being set to 25G, until I double checked the shown transceiver....Very odd bit of behavior on the ACI Leaf

Can Cisco or anyone comment?

Thank you

[MichalD]

According to Cisco's compatibility matrix https://tmgmatrix.cisco.com/, my C93240YC-FX2 requires a minimum software release of NX-OS 9.2.1 to fully support SFP-10/25G-CSR-S. Indeed, upgrading to 9.2.3 fixed my issue. The port will not auto-negotiate with the SFP-10G-SR on the other end and needs to be manually set to 10000 speed, but at least it works. Interestingly enough, to use the SMF flavor of the 10/25G SFP you need to be running minimum NX-OS 9.2.3 as even 9.2.1 is not enough. Looks like for the ACI you will need release ACI-N9KDK9-14.2(3j).