DDM/DOM diagnostics, optical power, BER, link flaps, lab methods
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…
After UniFi Network 10.0.140 / switch firmware 7.2.123 several operators saw SFP+ ports (UI optics, UACC-OM-MM-10G-D, MikroTik XS+DA0001 DACs, UACC-CM-RJ45-MG copper modules) flapping on US-XG-16, USW Pro Max, UDM Pro and USW-24-Pro units, with STP State Flapping alerts, ports blocked, and switches…
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…
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…
On Debian 8.11 (kernel 3.16) the poster ran ethtool -m on a Mellanox MT26448 adapter to read optical diagnostics (TX/RX power, temperature, voltage, thresholds) and got Cannot get module EEPROM information: Input/output error. Hardware involved: Mellanox MT26448 ConnectX-2, SFP+ optic with DDM…
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…
A QSFPTEK 10GBASE-T SFP+ module installed in port ix1 of a passively cooled Netgate 6100 reported 73 C through DDM although the room was at 20 C; the module is specified for 0-70 C and up to 2.5 W. The poster asked for known-good RJ45 SFP+ modules that stay within spec. Hardware involved: Netgate…
I finally moved my VDSL2 line off the ISP box and terminated it on the Turris Omnia itself, mostly so that PPPoE runs on the router instead of on a second device in bridge mode. The setup part was pleasant: seat the stick in the cage and the WAN interface simply moves onto the module, leaving the…
Two Flex System enclosures, each with an EN4093R 10Gb Scalable Switch (option 49Y4270) as the network module. Ports come back error-disabled after a chassis power event, and less often drop into the same state while everything is running. It is not always the same ports, which is what makes this so…
With an Aruba 2930F connected to a server through a Stornet-branded J9283D-SN passive 3 m SFP+ DAC, port 50 dropped the link immediately after it came up and port 52 flapped with the log message FFI : Port: 52 Excessive link state transitions. The same cable worked on ports 49 and 51, and fibre…
In a NANOG discussion about vendor lock-in, an operator described two concrete failures. First, a third-party optic answered I2C reads too slowly; the switch vendor's polling code did not handle the timeout and crashed the linecard control plane, and the vendor refused to treat it as a bug because…
The poster wanted to dump the EEPROM of a QSFP+ transceiver plugged into an Intel XL710-QDA1 and ideally read live DDM values such as received optical power, as they were used to doing with SFP modules on other adatpers. With i40e 2.0.23 and firmware 5.05 0x800028a2 1.1568.0, ethtool -m eth0…
On Ubuntu 18.04 (kernel 5.4.0, ethtool 5.3, i40e 2.8.20-k) the poster used 25G XXV710-based NICs bought from FS.com (FS part XXV710AM2-F2, Intel XXV710 chipset). Link and error-free wire-speed traffic worked, but reading a transceiver's DMI data with sudo ethtool -m enp4s0f0 failed with "Cannot get…
In the poster's data center several Cisco CWDM SFP/GBIC links stopped working: some ports went err-disabled (one with link-flap as the cause) and others simply showed notconnect. Troubleshooting included shut/no shut, reseating the modules, moving the CWDM SFPs to other ports, replacing the patch…
A Cisco Catalyst 3850-24XS with an SFP-10G-LR (1310 nm) connects over a single-mode cross-connect to a Tier-1 carrier's layer-2 DWDM equipment in the same data center. When the carrier shuts the circuit down, TenGigabitEthernet2/0/23 goes 'down, line protocol is down (notconnect)' yet 'show…
