Connecting 1G to a 10G Switch - Yes it can be done.

Recently we have helped solve a technical question that over the years has been asked a number of times.

Can I connect my 1G Switch to a 10G Switch?

This has lead to customers asking if they could use their SFP modules (1000Base) in the SFP+ (10G) slot and connect the switches especially as both use the dual LC connectors. Or optimistically asking 'can I use the SFP modules in SFP+ slot to have 1000Base or even 10G data links?'

This question has three area's to review.

Physical dimensions.

The standard's set by the world's vendors the Multi Source Agreement (MSA) mean that the physical size of a SFP (1000Base) and the physical size of a SFP+ (10G) are the same. The effect of the MSA also means that a 10G SFP+ will fit into a 1000Base port and vice versa. So physically the answer is yes.

Data Rate.

Most SFP and SFP+ will only work at their specific data rating and certainly will not 'Autonegotiate' between data speeds. So to get a solution the 10G switch needs to only work in 1000Base. Therefore the 10G switch must be manually restricted to 1000Base duplex maximum for the one port you require to be connected. Once that is completed it is possible you can use 1000Base SFP in both ports.

However, some 10G Servers, switches or routers will only accept a 10G SFP+ module. In this scenario you can use a 10G Multirate (1G/10G) SFP+ coded by Switch SFP. The multirate coded 10G SFP+ will accept the data and transmit / receive at 1000Base rate in the 10G device. 

Compatibility

The final point is to ensure you use the correctly coded vendor module. Note in certain configurations different vendor devices and be connected ie HP to Cisco - but always the correctly coded SFP/SFP+ will be required.

If you have any questions please contact the sales team who will be able to help and advise on these issues.