GLC - SMD VS SFP 10G SR - Connectivity Issues

[Waqas Javed]

Greetings,

My team is currenlty busy with a migration, we have C9800-L-F-K9 WLCs and C9500 40-X Core Switches. We were facing some issues regarding the GLC - SMD &  SFP 10G SR connectivity issues. Below is the detailed table for each senerio, I have few questions:

1. Is GLC SMD not compatible with C9800-L-F-K9 ?
2. With GLC SMD on both end using a multi mode, WLC port comes up (Physical) but the Core switch port  is down, why?
3. SFP 10G SR normally works with multimode, but we tested and its working with single mode as well, are SRs now compatible with single mode as well?
4. GLC SMD is comptible with both Single and Multi Modes on all devices? or there are certain devices on which it will not work like WLC C9800?
5. Would really appreciate if someone can expalin these without sending the Datasheet links just precise 1 to 2 lines or even a Yes or No will be sufficient as well

Wireless Controller To Core Switch
GLC SMD on both ends
Single Mode Fibre	Not Working
Multi Mode Fibre	Physical Connection up on the WLC & Down on the Core Switch
SFP 10G SR on both ends
Single Mode Fibre	Working
Multi Mode Fibre	Working
Core Switch to Core Switch
GLC SMD on both ends
Single Mode Fibre	Working
Multi Mode Fibre	Working
SFP 10G SR on both ends
Single Mode Fibre	Working
Multi Mode Fibre	Working

[balaji.bandi]

You need to provide complete SFP Model you used GLC SMD have different variant

Look at the model support Single mode and Multi Mode Fiber Support :

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

The one you mentioned not working ? - does the Devices recognize the SFP ? what logs you see.

If you using 1GB sfp and right fiber, if the port not come up try no speed negotiation on Cat 9500 and check.

About 10G SFP - check below (i have only working condition with 10G-LRM which can be used MM and SM  Fibre.)

https://www.cisco.com/c/en/us/products/collateral/interfaces-modules/transceiver-modules/data_sheet_c78-455693.html

[Waqas Javed]

Its an GLC - LH SMD

Tried no neg command as well, still the WLC and the Core Switch connection doesn't come up