Latest questions from the community.
An HPE FlexFabric 5950 48SFP28 8QSFP28 (JH402A) always downgrades an HPE JH419A 100G QSFP28 LC SWDM4 transceiver to 40G and never brings it up at full speed. Why?
A 1000BASE-T copper SFP (Arista SFP-1G-T) in an Arista switch does not link to a device that only rnus 100 Mbit/s, and a 10GBASE-T SFP+ does not fall back to a lower rate either. How does EOS handle speed negotiation for copper SFP modules?
An M290 with the optional two-port fibre module was fitted; can ports A0 and A1 be used as ordinary interfaces, for example for an ISP fibre handoff, and can a 1 Gb SFP be used in them?
What do the port states in the switchshow output of a Brocade Fibre Channel director or switch mean, and which of them point at the transceiver rather than the fabric?
A UCS 6332 fabric interconnect has only 40G QSFP+ ports, but the upstream switches are 10G. How can the FI be uplinked at 10G, and why does the breakout option not appear on some ports?
With auto-negotiation off and 10G configured on sfp1/sfp2 of a CCR1036-12G-4S (RouterOS 6.43.8), MikroTik S+DA0001 and Amphenol DACs still run at 1G and the Cisco side shows no link at 10G. Which part of this link should be checked first?
Cisco troubleshooting document: inserting certain SFPs (for example GLC-SX-MMD or third-party modules) into a Catalyst 3850 C3850-NM sub-module produces %PLATFORMPM-6-MODULEERRDISABLE: The inserted SFP module ... is not supported and %PM-4-ERRDISABLE: gbic-invalid ... putting ... in err-disable…
The poster asked how to test fibre cables from a switch. The guidance covers reading optical levels with show interfaces transceiver / show controllers, comparing TX and RX at both ends, and recognising that a reading of -40, -50 or -80 dBm means no signal is being received. Hardware involved…
A D-Link DES-3200-28 B1 switch logged DDM Port X optic module RX power exceeded the low warning/alarm threshold; the optical level looked abnormally low in the switch although the module measured fine when tested standalone. Hardware involved: D-Link DES-3200-28 B1, DDM-capable SFP. Reported…
Two Jetson Thor devices achieved 100G connectivity directly but with poor speed, and when each was connected to a 100G switch no link formed, although the same optics and cables passed a 100G loopback test against a different switch. The poster wondered whether insufficient speed was breaking…
The poster could not find documentation for the command service unsupported-transceiver and asked what it does and whether there are consequences. It is one of Cisco's hidden commands: without it IOS disables a port when a non-Cisco transceiver is inserted, because the OS reads the vendor field and…
A Huawei S6700 iStack did not form because the optical modules on the dedicated stacking ports 45-48 were of different types; the platform requires identical transceivers on those ports. The four ports 45-48 are the fixed stacking ports, and mixing, for example, an SR module on one and an LR module…
FS Box V2 is a firmware/coding tool kit for optical transceivers and DAC/AOC cables. It reprograms a module's compatibility code so it is accepted by a target switch platform, letting engineers adjust coding in the field or when a switch is upgraded to a version that no longer accepts the old code…
A customer with a 10Gtek ASF-10G-T 10GBASE-T transceiver could not read its EEPROM: ethtool -m ens802f0 returned Cannot get module EEPROM information: Operation not supported. The vendor attributed it to a firmware version mismatch between the NIC and the transceiver. Hardware involved: 10G NIC…
A proposed ixgbe patch would have let X550EM NICs recognise otherwise-unsupported 1G copper SFPs by treating them as 1G SX through a new module parameter, mirroring the existing unsupported-SFP handling. Without the change these NICs simply refuse the copper module, so operators wanting cheap 1G…
Huawei switches with third-party optics log SRM/3/SFPEXCEPTION ... Optical module exception, SFP is not certified daily, cluttering the logs during migrations even though the modules work. The modules pass traffic normlaly, but the daily SFPEXCEPTION traps flood the log buffer and the syslog…
On Huawei switches with 25GE ports the poster asked about using SFP+ transceivers and copper cables; per the troubleshooting docs, when a non-1 m copper cable is connected to a 25GE interface the RS-FEC function must be enabled or the interface goes Down, and mixing different optical modulles at…
Some Cotsworks SFF fibre modules ship with invalid data in the first EEPROM bytes (physical ID, extended physical ID, connector type) and with checksums programmed before the fields were finalised, so the Linux phy/sfp driveer does not detect them as valid modules. A kernel fixup rewrites the three…
An ODI DFP-34X-2C2 GPON ONU SFP failed to advertise its 2500BASE-X capability because its EEPROM (or virtual EEPROM) did not provide correct speed information to the Linux sfp driver, so the interface did not run at the expected rate. A kernel patch adds a quirk to force the right speed. Hardware…
On a Mellanox MSN4600C (ACS-MSN4600C) running SONiC in a T1 topology, the test testchcksfpusingethtool failed because ethtool -m sfp[ID] returned rc=1 with Cannot get module EEPROM information: No such device, i.e. the module EEPROM was not accessible on that platform during the test. Hardware…
On a Banana Pi BPI-R4 running OpenWRT 24.10.0 an SFP module failed with kernel logs failed to read EEPROM: -ENXIO and warnings that the module was slow to respond. The internet still worked but the log filled with the error, and the poster was unsure whether it pointed to a faulty stick, a GPON…
On an Accton Wedge100BF-32x the ONLP call onlpsfpeepromread returned QSFP EEPROM data with alternating bytes skipped, so vendor strings appeared with every other symbol missing; the same transceiver read correctly on an Accton AS7312-54x. The vendor name FINISAR CORP appeared at the wrong offset…
Adapter boards that, with a serial programmer, read and write transceiver memory across SFP, SFP+, SFP28, SFP112, QSFP/QSFP+/QSFP28, SFP-DD, QSFP-DD, XFP and OSFP. The software covers the MSA/CMIS memory maps, manages host/manufacturer passwords including brute-force search, changes…
An open hardware/firmware project to read and write the EEPROM inside SFP and SFP+ modules so their capailities and vendor origin can be inspected and modified. It uses an RP2040 microcontroller and exposes a USB Mass Storage interface. The project is a work in progress and does not yet document…
The poster wanted to flash four TRW-1310-1.25C-3 and TRW-1550-1.25C-3 SFP modules to work with an HP v1910-24G (JE006A) and asked about a programmer. The difficulty was finding the right firmware and matching serial numbers within one switch while keeping checksums valid. Hardware involved: HP…
A Python library to create, read and modify the 256-byte A0h page of SFP EEPROM per SFF-8472. It exposes named fields (vendor, part, serial, wavelength, bit rate, encoding, link lengths, diagnostics options), generates images from scratch or from a binary, and validates/recalculates checkssums. It…
A user guide for an SNR SFP/SFP+ reprogramming solution: USB programmer plus Windows/Linux software (FTDI drivers required) supporting SFP and SFP+ per INF-8053, SFF-8472/8431, INF-8077i and INF-8438. The workflow is connect, read the module to display vendor/model/wavelength, load a new firmware…
A USB coding-board product line to reprogram optical transceivers so they match different equipment vendors. Supported form factors span GBIC, SFP, SFP+, SFP28, XFP, QSFP, QSFP28, QSFP-DD plus RJ45, DAC and AOC. The software reads, decodes, edits and writes module memory, ships about 400 well-known…
A web-based (Web Bluetooth) GUI for the UniFi SFP-Wizard device that reads SFP EEPROM, saves backups as .uieeprom files and writes from a prior backup. Limitations: the API does not flash directly; the dump goes to the device snapshot buffer for manual confirmation on the hardware; newer firmware…
A set of bash scripts using i2c-tools to modify SFP module EEPROM. Hardware is an STM32 configured as a USB-I2C adapter (or a Raspberry Pi / mainboard SMBus) with a Cisco Twingig adapter as the SFP breakout. It handles the default Cisco Finisar module password 0x00000000 and recalculates checksums…
