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Cisco Employee

Connectivity issue occurs when fiber network module is used on a FireSIGHT System

After deploying a FireSIGHT System with Fiber Network Module (Netmod), connection is lost between the end devices.

  • Firepower / FireSIGHT System
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Cisco Employee

When you deploy a FireSIGHT

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 StateLink Status
Local DeviceRemote DeviceLocal DeviceRemote Device

Off

OffUpUp
OffOnUpDown
OnOnUpUp
OnOffDownUp

 

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.

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