Choosing SFP modules for a MikroTik CRS328 to HP 1820 link and outdoor fibre
5
The poster needed to connect a MikroTik CRS328-4C-20S-4S+RM to an HP 1820-24G-PoE+ over 200-500 m of outdoor aerial fibre and asked which SFP modules to buy and how to verify compatibility before purchase. The HP compatibility table listed only J4859C as a single-mode SFP, while MikroTik offered S-31DLC20D; the poster wanted to know whether one module of each type would link to each other over single-mode fibre and whether two fibres were required. The discussion also covered single-mode versus multimode cable choice.
- Hardware: MikroTik CRS328-4C-20S-4S+RM, HP 1820-24G-PoE+
- Transceivers: HP J4859C, MikroTik S-31DLC20D
- Form factor: SFP
Symptoms / messages:
pre-purchase compatibility question
vendor lock concern
Comments 3
Both modules are 1310 nm 1G LX types, so they will interoperate; each uses a duplex pair, so the cable needs an even number of fibres.
Prefer single-mode fibre: it is cheaper and easier to source today, multimode only makes sense to stay compatible with existing plant.
A member with a programmer warned that many vendors lock SFPs in firmware; some locks can be bypassed with undocumented commands, but not always, so buy modules with a return guarantee or ones listed as compatible.