RB260GS - SFP Module - Not working - no RX just TX

Hi!

Currently i am using TPLINK-MC220L. This Device supports only modules up to 10km.
I have installed a 40 km Module, but after 15km the signal were loss.

Now i like to use RB260GS. Is this Model able to power up a 40km SFP Module?

Thanks.

Check the actual power requirements of proposed 40km module. The specs on the TP-Link part are simply based on the normal IEEE standards. Did you check the physical link characteristics against the specs of the 40km modules (assuming you have the data from the installer/contractor/provider).

The Module provides 19dB of output. The physical attenuation is at 12dB, so 7dB is enough for the link to work.

I replaced the TP-Link MC220L with a RB260GS, the link comes up but i have no RX.
On Side A, the SFP-Link-LED is on. On Side B the LED is off.. That is odd.

SFP
Auto Negotiation	
Module Present	yes
Vendor	CISCO
Part Number	SFP-GE-BX40-U
Revison	1.0
Serial	1140400798
Date	14-02-11
Wavelength	1310nm
Supported Link Lengths
Single Mode Fiber	40000m
50um OM2 Fiber	
62.5um OM1 Fiber	
Copper	
Status
Loss Of Signal	no
Temperature	38C
Voltage	3.2304V
Tx Bias	17.632mA

The same behavior i had with an 10km Link. Both TP-Link MC220L had a full functional link. After placing the SFP from one MC220L to RB260GS the link came up, but i had 0 bytes in RX.

Some forum members achieved the same strange behavior.

What is wrong with RB260GS?

There may well be something not working between the 260 and the SFP module but “19db” of output is largely meaningless unless the reference point is stated. “db” is not an absolute unit - it is a relative (typically power) measurement.

Have you calculated the absolute signal which should be received and checked that against the module’s stated sensitivity?

Sorry, but anything is wrong with the RB260GS.

Now i ordered new SFPs with Multimode to test both RB260GS units.
Both SFP-LED are on, but there is no data communication between both devices.

I tested both SPFs in two TP-LINK Switches and in DELL Switches. In both switches, the modules worked fine.

SFP
Auto Negotiation	
Module Present	yes
Vendor	CISCO-FINISAR
Part Number	GLC-SX-MM
Revison	10.0
Serial	FNS1118A283
Date	11-02-24
Wavelength	850nm
Supported Link Lengths
Single Mode Fiber	
50um OM2 Fiber	550m
62.5um OM1 Fiber	270m
Copper	
Status
Loss Of Signal	no
Temperature	
Voltage	
Tx Bias

https://www.diigo.com/item/image/2wcof/s82d

Installed Firmware Version 1.12

Was that test with a short MM patch cable? That looks like a fairly standard - I would have expected it to be supported.

100m MM patch cord.

Unbelievable !!! After resetting both devices to “Factory defaults” the modules worked. I made 3 power cycles and the Fibre-Link was established and working fine without one interruption.

I did not configure anything, after i picked the units from packaging. I have installed the SFP-Modules, powered on the units and the SFP wont work. I upgraded from Firmware v1.9 to v1.12, but nothing changed. After a “factory reset” both devices linked via SFP.

So i thought: “Very good, so lets test the 40km Modules”… I powered down both units, inserted the new 40km SFPs and powered the devices up. But the same problem as before… TX but no RX… After “factory reset”, the unit worked and a link via SFP was established…

What the hell is wrong with that Firmware?
It can not be the answer to “factory default” the units every time i change the SFP-Module.