Transceiver and switch sfp port doubt regarding auto negotiation?

[13jobsp90]

I have a doubt if a transceiver eg - SFP 10LR which is sfp+ form factor (as mentioned in the cisco sheet) and 1 g sfp port switch? Will the transceiver work  in the switch? 

[M02@rt37]

Hello @13jobsp90 

SFP-10LR transceiver, which is an SFP+ form factor designed for 10G speeds, will not work in a 1G SFP port on a switch, even though both use the SFP form factor.

While the physical connectors are similar, SFP+ is built for 10G Ethernet, and SFP is designed for 1G speeds. Since the transceiver expects a 10G interface and the 1G port only supports 1G, the switch will not recognize or establish a connection with the SFP-10LR in a 1G port. You would need a 1G-compatible transceiver (such as SFP-GE-SX) for proper operation in a 1G port.

[13jobsp90]

but the transceiver is sfp+ so it can downgrade the speed?

[Joseph W. Doherty]

Usually not.

[M02@rt37]

Check here for the compatibility matrix for SFP modules regarding platforms:

https://tmgmatrix.cisco.com/

[Joseph W. Doherty · Accepted solution]

No, it won't.

The 10g SFP+ needs either a dual speed gig/10g (SFP+) port or a 10g SPF port.

I.e. SFP+ port are multiple speed capable, but optical transceiver, generally, are not multiple speed capable.

Oh, and in the Cisco world, ideally, a particular transceiver is supported on their device (device may require minimal IOS version too).