Connect a QSFP+ cable between a 5520-48W and a x770-32q

[MartinS]

Hi,

I am attempting to connect a 5520-48W to a x770-32q using a QSFP+ cable, but when it's connected, there's no link light and no sign of the link being up at either end. I believe I have enabled the right ports.   On the 5520-48W, I am using one of the two large Universal Ethernet QSFP28 ports. On the x770-32q I am using port 39, which is a 40G/10G QSFP+ Ethernet port.  I am using an Extreme Direct Access Copper (DAC) QSFP+ cable to connect the two together. Is this cable compatible between these two ports on these two switches ? 

Thanks,

Martin

EDIT: I discovered the problem. I had stacking support enabled on the 5520 from the previous setup. I disabled stacking support, rebooted, and now it's working. I can see the link is up correctly.

[CThompsonEXOS]

Hi Martin,

If you do "show ports <ports in question>" on the 5520, do they show as NP?

Thanks,
Chris Thompson

[MartinS · Accepted solution]

Hi Chris, thanks for taking the time to reply. I discovered the problem. I had stacking support enabled on the 5520 from the previous setup. I disabled stacking support, rebooted, and now it's working. I can see the link is up correctly.

[CThompsonEXOS]

Glad you were able to fix it.  That was my guess but only because I have also banged my heard with the exact same problem.