What to check if an interface with SFP Plus module is showing down. How to view supported and unsupported SFP SFP+ or QSFP module transceiver details for dataplane interfaces. The article provides information on troubleshooting port flaps or link down issues. On a big industrial plant we've replaced an old HP switch with a brand new couple of C2960x switches in stack configuration and ever since then, every 6/8 hours or so, the two fiber optics links of switch #2 go down at once. These are connected to a ring of 3 similar other access switches, that. After inserting an optical module, the switch interface indicator does not light up, and the link cannot communicate normally. All PaloAlto Hardware-based Firewalls. If the link is not up or the LED is not solid green then, Check if the cable used is. This document describes how to troubleshoot fiber optic interfaces by addressing some of the fiber optic module and cabling specifications. This includes Doppler. I have an M4250-10G2F switch, I am connecting an SFP module - AVAGO AFBR-709SMZ. While in the terminal command "show fiber-ports optics-info all" the SFP module is recognized and claims to be supported, I see that the link is down, and no LED turns ON on port 11. All seems ok most of the time but we noticed that once or twice a week, one fiber port is down (according to the log), so an important part of the network which access through.