Differnce between GLC-SX-MM vs GLC-SX-MMD

[ZK916]

Hello,

I am just trying to find out if there is a difference between the GLC-SX-MM vs the GLC-SX-MMD SFPs.

Cisco's document shows only shows the MMD but not that MM. Any thoughts?

https://www.cisco.com/c/en/us/products/collateral/interfaces-modules/gigabit-ethernet-gbic-sfp-modules/datasheet-c78-366584.html

Thanks in advance.

~zK

[M02@rt37]

Hello @ZK916 

The main difference between the GLC-SX-MM and GLC-SX-MMD SFPs is related to the Digital Optical Monitoring (DOM) feature. "MMD" in GLC-SX-MMD stands for "Multimode Data-link Distances," and it indicates that the SFP module supports DOM. The DOM feature allows you to monitor real-time parameters of the SFP, such as optical transmit and receive power levels, temperature, and voltage.

On the other hand, the GLC-SX-MM does not support the Digital Optical Monitoring feature. If you don't require the monitoring capabilities provided by DOM, the GLC-SX-MM should be sufficient for your needs.

[ZK916]

M02@rt37 Thanks for your input. 

I used the Compatibility matrix to find out if this network module (C9300X-NM-8Y) supports the GLC-SX-MM but this particular SPF was not listed. The GLC-SX-MMD is listed, thus supported. So, does this mean that this particular NM (C9300X-NM-8Y) doesn't support the GLC-SX-MM but the GLC-SX-MMD is supported? 

https://tmgmatrix.cisco.com/?npid=4304 

Thanks in advance. 

~zK 

[M02@rt37]

@ZK916 

While the GLC-SX-MM is not explicitly listed in the compatibility matrix for the C9300X-NM-8Y network module, it's essential to understand that Cisco devices often maintain backward compatibility. The absence of the specific SFP (GLC-SX-MM) in the matrix doesn't necessarily mean it won't work.

The GLC-SX-MMD is an updated version that includes DOM capabilities, and it's becoming more common in modern Cisco equipment. In many cases, devices that officially support the GLC-SX-MMD can also work with the GLC-SX-MM.

Since you are using the correct patch cable (MM) and your backbone is also MM, then yes.  The GLC-SX-MMD and GLC-SX-MM are compatible !!