Negotiation between SFP 1Gb and SFP + 10Gb

[JorgeQ12]

Hello, I want to ask a very basic question, but it has me with doubts. I am entering the Meraki world.
I need to install a 10Gb SFP + on a MS425-16 Switch, which is connected to another switch NOT Meraki, but with a 1Gb SFP.
Will the Meraki SFP + negotiate at 1Gb against the other switch without problems?
Later it is planned to upgrade all switches to 10Gb.

Thank you!

[Inderdeep]

@JorgeQ12 : SFP and SFP+ modules look exactly the same. And as they have the same size, your SFP transceiver will fit seamlessly into an SFP+ switch port and vice versa. However, the connection won’t work as you expect it to. Or, worse even, it won’t work at all. If you plug an SFP device into an SFP+ port, the speed will be locked at 1 Gbps. Plugging an SFP+ module into an SFP port delivers no results at all, as the 10G transceiver can never auto-negotiate to 1Gbps.

https://documentation.meraki.com/MS/Other_Topics/MS_Switch_SFP_and_SFP__Overview#Are_other_Cisco_SFP... 

[cmr]

@JorgeQ12 you need to use a 1Gb SFP in the MS425 for now to make the link work.

[JorgeQ12]

@Inderdeep Thanks.! 

I understand. But at the level of interface negotiation in each switch, being the MS switch the one with the 10Gb SFP +, and the other switch with its 1Gb SFP, the link between them would not be negotiated at the lowest speed, which would be at 1Gb?

[DarrenOC · Accepted solution]

Nope. Both sides need to have the same SFP type I.e 1gbps at both ends or 10gbps at both ends.

[Inderdeep]

@JorgeQ12 : This is what @DarrenOC says is correct. Although if you have SFP+ on both sides you can set it for 1 Gbps speed but you should have same type of SFP or SFP+ module on both sides.

[BlakeRichardson]

@Inderdeep  That is correct provided the 10Gb SFP modules support backwards compatibility, not all modules do. 

[AKM]

For MX95 : can we use  10G SFP  wan port(interface2) for LAN connection for meraki access switch over 1Gig of MDF Module on both sides

[cmr]

@AKM the WAN ports are for WAN access and the LAN ports for LAN access.  However on the MX95 you have SFP+ ports on both WAN and LAN.  Both SFP+ ports can connect over fibre at 10Gb or 1Gb and the speed is defined by the transceiver.

[AKM]

thanks for reply, can't we change the role of WAN port to LAN ?

[cmr]

@AKM unfortunately not.