In NGN application, the NE40 is connected to UMG through two GE ports. Generally, UMG uses active GE to transmit information; if the active interface fails, it is switched to the standby automatically.
Symptom: Once NE40 is upgraded and reset, both the physical and protocol of GE connecting to UMG are down, but the GE interfaces at UMG side often have one or two up alernatively (according to LED). The LPU that both GEs switch over repeatedly.
1. Enable a loop for GE at NE40 and UMG respectively, and the physical is up, indicating the physical interface is normal.
2. For the interconnection between both sides, the physical at UMG side could be up, indicating that the tailfiber is normal.
3. Perform shut/undo shut command for the interface of NE40, but the problem persists.
4. Chang the auto-negotiation of interface of NE40 to forced mode. The physical and protocol are up; UMG GE LPU stops switchover, and the active could work well.
The port may be problematic after upgrade or the negotiation is problematic.
That the interface mode needs to change after upgrade is because UMG has ever changed the negotiation mode. In other words, the both sides were set to auto-negotiation before, and UMG changes it to forced mode, so NE40 cannot negoiate for interface again but both could work well. However, once NE40 is reset, it initiate negotiation again, but it fails(that the physical of NE40 is down, and that of UMG is up, indicates UMG is in forced mode, because it is up if only the physical connection is normal, regardless of negotiation) because the negotiation code flow at both sides differ, leading to repeated switchover of GE LPU of UMG.