The core switch is connected to two fiber optic cables

Using two fiber optic cables between a core switch and other switches provides redundancy and higher bandwidth, typically implemented with SFP modules and proper network topology.Fiber Connection Basics

When connecting a core switch to other switches using fiber, each fiber cable should terminate in an SFP (Small Form-factor Pluggable) module on both ends. The SFP modules convert electrical signals from the switch into optical signals for transmission over fiber, and vice versa . For short distances (under 100 meters), multi-mode fiber (MMF) is usually sufficient, while single-mode fiber (SMF) is preferred for longer distances . LC connectors are commonly used for patching fiber cables .

Redundancy and Bandwidth

Using two fiber cables allows for redundancy and increased throughput. This can be implemented via:

• EtherChannel (Link Aggregation): Combines both fiber links into a single logical connection, providing higher bandwidth and automatic failover if one link fails .
• Redundant Links: Each fiber acts as a backup; if one fails, the other maintains connectivity. This is simpler but does not increase bandwidth. Avoid creating loops without proper protocols like Spanning Tree Protocol (STP), as loops can disrupt the network .

Network Topology Considerations

• Star Topology: The core switch connects directly to each distribution or access switch. Each fiber cable is dedicated to a single switch, which simplifies management and reduces the risk of network loops .
• Ring or Cascading Topology: Less common today; a failure in one switch can affect downstream switches. Modern networks favor star topology for reliability .

Practical Tips

1. Match Fiber Type: Ensure both ends use the same fiber type (MMF or SMF) and compatible SFP modules .
2. Patch Cables: Use LC-LC patch cords for connecting SFP modules to fiber panels or switches .
3. Test Links: Verify optical power levels and connectivity before deploying in production.
4. Consider Future Expansion: If more switches will connect to the core, plan for additional SFP ports or fiber strands. By following these practices, connecting a core switch with two fiber optic cables ensures high-speed, reliable, and redundant network connectivity.