fields to compare to determine server to switch sfp compatibility?

[baselzind]

What fields have to match between a server sfp and a switch sfp in order to determine they are both compatible? for example wave length , mmf...etc

[Leo Laohoo]

Servers, more than always, support multi-mode SFP.  Start with that.  

[baselzind]

but is both sfp being same mmf and speed is enough to decide they are compatible and buy them? or is there more parameters to match?

[Karsten Iwen]

Look for matching types. For example the switch uses a Cisco compatible SX-SFP and the server uses a "server-vendor" compatible SX-SFP.

[Leo Laohoo]

Cisco Catalyst switches support 100 Mbps, 1-, 10-, 25-, 40- or 100 Gbps. 

Some servers support different speeds.

[Syed Hassan Shah]

Hi ,

let me help you out here with a simple check to run for future as well in order to avoid any confusion.

Part-1 SFPs

1- SFPs on both the sides are recommended to be of same type, not necessarily of same OEM
for example if switch has an SFP-10G-SR, then the server must have an equivalent SFP for connectivity.

2- SFPs must be decided first from the server side, Why ? if you miss the FCoE parameter while selecting an SFP, you will face issue if you chose the models which did not support FCoE.

3- Match and decide the type of connector going to be used with the SFP, If you are using a Dual LC connector SFP at one side then for sure you need to get the Dual LC connector. People often make mistake of ordering a selection of SFPs based on the word LC mentioned and then fall into trouble once the order is arrived due to the mismatch of switch and server side inventory.

Part-2 Fiber Cables

1- Decide which Fiber optic cable type is going to be connected between the switch and the servers.
For example if you have chosen a dual LC connector type SFP for the design, then you will need to order the dual lc fiber cable to support your connectivity.

2- Decide the mode & type of fiber optic to be used. MMF or SMF only does not finalize the compatibility for the overall connectivity.
For example you ordered SFP-10G-SR to connect between the switch and the server but the distance between your both ends is greater than 80 meters, you may have to order OM3 or OM4 MMF cable otherwise if mistakenly you ordered lower than OM3 or decided to use any other cable from your existing inventory which might be an OM2, you would be in trouble.

For detailed compatibility matrix against each Cisco SFP you may check out Cisco Transceiver Compatibility matrix.

Please mark all the helpful responses

Regards

[baselzind]

what is the FCoE parameter? is one sfp have FCoE parameter and the second dont it will not work with it?

[Syed Hassan Shah]

Hi baselzind,

FCoE is Fiber Channel over ethernet, this is used when you want to traverse the combination of LAN and SAN traffic over your layer 2 connectivity. If you select mismatched SFPs in this case you would not be able to traverse the SAN traffic whereas LAN traffic would work.

Implementing FCoE is a strategic design decision which not only combines the two different traffic types but also saves the cable bulk which is separately required for SAN (Storage) connectivity.

Please mark all the helpful responses or solved when it addresses your query.

Regards

[baselzind]

but isn't there any other parameters to check for compatibility between a server and switch sfp? like the wavelength number? even if both sfp match in fiber type and speed?

[Leo Laohoo]

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@baselzind wrote:
like the wavelength number? even if both sfp match in fiber type and speed?

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You are talking about CWDM/DWDM. 

If someone has designed servers to use CWDM/DWDM optics then it is a very, very bad design.

[baselzind]

No I mean like every sfp has a Receiver and Transmitter Optical Characteristics which are measured by wavelength. And I'm wondering if they have to match or not like for example the below cisco sfp 

should these characteristics match with the server sfp optical characteristics as well?

[Leo Laohoo]

No, that is different.  

The wavelength of the optics need to be the same, i. e.  SR to SR or LR to LR.  

And then the speed needs to be the same as well. 

[baselzind]

What about the transmit and receive power? do they have any importance when matching between two sfp?

[Leo Laohoo]

As long as both ends operate within the limits, the link (and the optics) are fine.

All new optics nowadays are DOM and they switch can detect if the tx/rx power falls outside the allowed limit.

[Tom Randstrom]

In your example table, the 10GBASE-SX identifies the specification that the SFP meets. The 10G = 10 Gigabit speed, the SX identifies the link reach (short).  Thus, if you use two 10GBASE-SX compatible transceivers on the ends of the link, then you don't need to worry bout the wavelength and optical characteristics.  There are different transceiver specifications to support the various length fiber links (-LX, -ZX, etc) that cover most applications.  These different specifications may use different fiber types and Tx/Rx characteristics to meet the link and speed lengths.