Latest questions from the community.
SFP+ DACs linked MikroTik-to-MikroTik and OLT-to-OLT, but between a V-SOL EPON OLT 16008D and a CCR2004-1G-12S+2XS or CRS326-24G-2S+RM the OLT reported the interface as disconnected. The same DACs were recognised on both platforms, so the poster suspected a cross-vendor auto-negotiation or…
On a CRS226-24G-S2+RM (RouterOS 6.42.11 long-term) the SFP+ port stayed at no link, not running, slave after a power loss, while software reboots were fine; disabling and re-enabling the interface fixed it manually. The problematic module was a Huawei MA5671A GPON SFP, other SFPs behaved, and the…
After upgrading a CRS305-1G-4S+ to SwOS 2.12, SFP-GE-T 1000BASE-T copper SFPs stopped linking although the switch still identified them in the SFP tab; the same modules kept working on a CRS317-1G-16S+ with the same firmware. Modules inserted before the upgrade continued to work, modules inserted…
On a CRS326-24G-2S+ with RouterOS 7.7 three third-party 1G RJ45 SFPs failed: an HP 453156-001 (FCLF-8521-3-HP) showed no-link with auto-negotiation: failed, a Foundry E1MG-TX showed no-link with sfp-rx-loss: yes even with manual speed, and a Ubiquiti UF-RJ45-1G also stayed at no-link. Hardware…
A MikroTik CCR1036-8G-2S+ with S-31DLC20D 1.25G single-mode SFPs reported link OK but no traffic flowed; TX power was blank and RX was -9 dBm. The identical module on the same fibre worked in a CCR1036-12G-4S. Port disable/enable, forcing 1G full duplex on both ends and support tickets did not…
Two FS.com 1G BiDi SFPs (1490/1310 and 1310/1490 nm) in a MikroTik CRS326-24G-2S+ running SwOS 2.9 detected incoming light around -6 dBm but never established a link; the same optics linked on a Netgear switch. The poster asked whether a manual speed setting was needed and whether RouterOS would…
A first-time SFP+ deployment between a UniFi 16XG switch and a Tehuti Networks TN9310 SFP+ adapter, with transceivers the reseller called compatible, produced an Rx fault indication in the UniFi controller. Swapping the fibre ends (polarity) did not help. Hardware involved: Ubiquiti US-16-XG…
FS.com 40 km 1550 nm SFP+ modules (item 11592) showed their information in a MikroTik CCR1016 but never linked in the SFP+ ports, whatever the auto-negotiation, 1G/10G speed or flow-control settings; standard 10G modules (item 29851) worked in the same ports, and the 40 km modules ran at 1G in…
A MikroTik CSS610-8P-2S+ (SwOS Lite) needed to connect its SFP+ ports to a Cisco Nexus 5596UP. The ports showed the transceivers in the web UI but no link, after trying several fibre cables and transceivers. The switch web UI listed vendor and type for each module, yet the port stayed at no-link…
A pfSense router on a Supermicro R210 II with an AOC-STGN-i2S (82599-based X520 clone) was connected throguh an FS.com SFP+-to-RJ45 module to a cable modem with a 2.5 Gbps port. No link negotiation happened; pfSense offered only auto and 10G speeds and never 2.5G. Hardware involved: Supermicro…
An embedded device with a 10GbE SFP transceiver kept logging power warnings above 800 mW and occasional errors when fed by an NVIDIA/Mellanox MMA2P00-AS 10/25G transceiver over a 2 m OM3 LC patch. The poster assumed transmit power is negotiated between the two ends and asked whether a failed…
Mellanox ConnectX-3 MCX314A-BCBT and MCX354A-FCB cards (firmware 2.42.5000, driver 5.50.14740.1) were detected in Windows 11 and Ubuntu 22.10 but no optical transceiver ever emitted light: Cisco QSFP-40G-SR-BD, Cisco SFP-10G-SR and Mellanox MFM1T02A-SR were tried on LC-LC OM3, aross three…
Used Intel 82599ES 10-Gigabit SFI/SFP+ NICs from eBay were connected with 10Gtek SFP+ DACs and, via QNAP switches, with 10Gtek SR transceivers over OM3. On Linux dmesg looped NIC Link is Up 10 Gbps / NIC Link is Down; on FreeBSD the interface showed no carrier and DHCP failed. allowunsupportedsfp=1…
In a home lab with an Aruba S2500 PoE switch and an Intel X520-DA2, three of thirteen cheaply bought Intel AFBR-703SDZ-IN2 SFP+ modules (around 15 USD each) failed within three months: links dropped with dark activity LEDs, two on the switch side and one on the NIC side. Warm and cold reboots…
With two dual-port Mellanox ConnectX-4 cards, a MikroTik SFP+ switch, 1 m OM4 patches and mixed 10G/25G transceivers from several vendors, one NIC port showed link UP but got no DHCP and could not route, 25G transceivers negotiated only 1G, and previously stable 10G links dropped intermittently…
