how can i use 10g on 40g 450 switches

[Jon_Cole]

We are purchasing a pair of MS450's as our user core. The idea is to future proof ourselves for 40g connectivity, however, currently we only have 10g uplinks in use. What should we do to use the interfaces because the interfaces arent 1/10/40 g interfaces.

[cmr]

@Jon_Cole Meraki switches don't support the QSFP(+/28) breakout cables so the ports are a single 40Gbps connection, you cannot get a 10Gbps SFP+ connection.  You'll need some switches from lower in the range that have QSFP+ uplinks and SFP+ downlinks like the MS425 models

[Ryan_Miles]

You should be able to use the CVR-QSFP-SFP10G adapter to use a 10Gbps transceiver in a 40Gbps port on the 450

https://tmgmatrix.cisco.com/?npid=2301

[cmr]

Thanks @Ryan_Miles I was not aware of that rather useful adapter 😎

[KevinFor2021]

some quick notes on the MS450 with 10G/40G connections on what "works" & "broken" with the latest Beta 15.4 Firmware...  We can connect MS450 to MX95 via 10G using 3rd party 10G SR modules  and the Cisco CVR-QSFP-SFP10G 40G adapter - no problems... (many 3rd party 40G/10G converter modules failed - thankfully we found a Cisco Refresh version of the adapter module but still expensive)..  MS450 to Mellanox NIC with 40G Direct attach 3rd party also works fine..

What is "broken" is trying to link MS450 to MS390 via 40G module (MA-MOD-2X40G) using a Meraki 40G cable MA-CBL-40G-1M no lights nothing... Direct attached cable should work... Support couldn't resolve... the only workaround is to buy two 40G SR-BD modules and your own OM4 Cable which is crazy /expensive  if you only need 1/2 to 1 Meter uplink.. between two switches..   Regarding the MS390 40G to MX95 10G link above even with Meraki SR Modules if you unplug either module and plug back in the Green light comes back on but you cannot ping the other side unless you reboot the MS390 and MX95 - so I think the MA-MOD-2X40G module has some issues on the MS390