Popular discussions about programming, compatibility and testing of optical transceivers.
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?
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?
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?
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…
Home rack, and the RB5009 has exactly one SFP+ cage. I wanted a second copper gigabit uplink out of it rather than pulling fibre across the room, so a copper module went in instead. MikroTik RB5009UG+S+IN, RouterOS 7.1rc4 MikroTik S-RJ01 1000BASE-T copper SFP in sfp-sfpplus1 Cat6 patch, about three…
Small vSphere cluster, two 10G uplinks per host into a pair of top-of-rack switches. After the ToR was rebooted for a firmware update, part of the VMs on one host went silent and vMotion failed on both uplinks - yet ESXi never marked anything down and the adapter LEDs stayed lit the whole time…
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…
We are standing up four DGX Spark nodes for disttributed training and hung them off a MikroTik CRS812-8DS-2DQ-2DDQ. The plan was one 400G QSFP-DD port on the switch feeding two nodes at 200G each, so a couple of breakout cables cover the whole cluster. MikroTik CRS812-8DS-2DQ-2DDQ, QSFP-DD ports…
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…
We look after the switch management firmware on our own hardware, and ever since the SP/FPGA interface was changed from memory mapped buffers to a FIFO, the transceiver inventory has been coming back as junk on some ports. QSFP28 optics, all of them AFBR-89BDDZ out of the same batch reads go over…
I am putting together a switchless Fibre Channel setup at home: one box holds the storage and has to act as the FC target, the other two are plain initiaators. No FC switch in the middle, just direct cables between HBAs. Hardware: QLogic QLE2694 in the storage box, the one that should be the target…
We push traffic from a lab server into a CRS518-16XS-2XQ over a 100G QSFP28 uplink, and it leaves the switch through a MikroTik S+RJ10 copper SFP+ into a plain 1G RJ45 host. The receiving side is missing a large share of the packets and I cannot pin it on anything obvious. Setup: MikroTik…
