When you deploy a FireSIGHT System (also known as 3D System) with Fiber Network Module and the auto-negotiation option is not properly configured, your end-devices may experience connectivity issues.
The reason for this issue is the Auto-Negotiation configuration. If you have misaligned Auto-Negotiation settings, One device will be looking for certain data before bringing the device up, but the other will never send those.
Per the IEEE 802.3 Standard, it is not necessary to specify a mode of Auto-Negotiation. Therefore, if one device uses Auto-Negotiation, and the other is not, you will not have link between them. The following table explains the differences that could exist between two fiber devices:
| Link Negotiation State | Link Status |
| Local Device | Remote Device | Local Device | Remote Device |
Off | Off | Up | Up |
| Off | On | Up | Down |
| On | On | Up | Up |
| On | Off | Down | Up |
To prevent this from happening, ensure that both of your devices are configured for Auto-Negotiate. A FireSIGHT System does not support disabling of Auto-Negotiation on fiber network modules. It is a best-practice to ensure all of your fiber interfaces are set to Auto-Negotiate, however some devices may allow you to hard-set the Speed/Duplex of the interface.
