Latest questions from the community.
Standing up 25G uplinks from a QFX5120-48Y towards a second switch and a couple of new servers. Before I hand the segment over I want the link settings written down properly, and I cannot find where auto-negotiation lives on these ports. Juniper QFX5120-48Y 25G optics in the SFP28 cages et…
We are refreshing the core of a small office and put in a pair of Aruba CX 6200F. The link between the two switches is meant to be a 10G trunk on the SFP+ uplinks, and I cannot get either box to admit that 10G exists on that port. 2x Aruba CX 6200F Switch Series, trunk on port 1/1/25 Cisco…
A good half of my work is putting one company's optics into another company's switch, so I spend a lot of time asking a module what it thinks it is. My toolbox for that is currently one command deep, and I would like to know what else is worth putting on the bench machine. Linux boxes with SFP+ and…
Small office, we are dropping the ISP-supplied box and terminating the fibre straight on the router. The handoff is AON, the provider only asks for a VLAN tag, no PPPoE and no ONT registration. What is in the rack: TP-Link ER7412-M2 V1, firmware 1.0.1, fibre into port 11 (SFP WAN) a TP-Link…
We are pushing Wi-Fi into an outbuilding on a campus site. The only fibre going that way is a single strand, so the plan was to hang an AP-375 out there and feed it over a BiDi pair we already had on the shelf. Aruba AP-375, ArubaOS 8 Cisco BiDi SFP in the AP cage, its matching partner wavelength…
A dual-port ConnectX-5 (MT27800, firmware 16.35.1012, MLNXOFED 5.8 on BC-Linux 8.2) connected to a switch with a DAC would not recover after the cable had been connected and disconnected about fifteen times: the port stayed in State: Polling with Physical state ETHANFSMABILITYDETECT, and mlxlink…
On a Mellanox SN2410 (MLNX-OS 3.6.4112) a 100G port connected to a Chelsio adapter through a 2 m unequalised QSFP copper cable would not link when FEC was disabled; no HSS lane signal was detected on the adapter side. The poster required FEC-off operaation and asked whether the switch supports it…
I look after a two-building site and the access switches were replaced with Aruba 2540s a while back. The fibre between the buildings has not been touched, but since the swap the uplink refuses to come up. Aruba 2540 on our side, ports 51 and 52 used for the uplinks Aruba J4858D 1000SX in the 2540…
Mellanox-branded Q-4S28AO03 3 m QSFP28 AOC 1x4 breakout cables (100G with FEC) that worked under Onyx 3.9.1908 stopped linking after an upgrade to Onyx 3.10.x. The ports reported Cable speed not enabled and, with auto speed, Negotiation failure; supported speeds showed 1G/10G/25G but the actual…
A Synology RS3614xs+ with a supported Intel X520-DA2 rejected the wrongly ordered SFP+ modules as unsupported. Putting options ixgbe allowunsupportedsfp=1 into /etc/modules.conf had no effcet, and even when the kernel log showed ixgbe: allowunsupportedsfp Enabled the driver still reported failed to…
Adding a 100G link between two racks on an X690 that has been quietly doing 10G access work for a couple of years. The uplink cage will not take the speed at all. ExtremeSwitching X690-48x-2q-4c 1 m QSFP28 direct attach cable, Q28+CR41m port 57, one of the QSFP28 uplink cages The cable comes up as…
A site decommission left me with a drawer of pulled Cisco optics, a mix of GBICs, 1G SFPs and 10G SFP+, and I have to decide which of them go back into production and which go in the bin. The GBICs I have put aside for now, since nothing on the bench takes them, so everything below is about the SFP…
A Mellanox ConnectX-4 Lx (MCX4121A-ACAAx, firmware 14.32.1900) in a Ryzen desktop (Fedora 41 and Windows 10) detected the interface but reported Cable is unplugged with two FS.com SFP28-25GLR-31 modules and a 40 m single-mode LC duplex patch; a MikroTik router recognised the same optics. The poster…
A Mellanox ConnectX-3 40GbE NIC connected with Mellanox QSFP passive copper cables (MC2210126-005) to a Dell PowerConnect 8164 (firmware 5.1.4.5) produced a link-up event for a few seconds followed by a permanent link-down. The same cables worked NIC-to-NIC, and Dell refused support because the…
We run a couple of IBM Power boxes next to a small SAN, and I am trying to write down a sane spares policy before the next hardware maintenance renewal. The part I cannot pin down is the transceiver itself: on some adapters it looks like a field-replaceable part in its own right, on others a…
