Use link aggregation (LAG) to connect the OLT to the aggregation switch, combining multiple physical ports into a single logical interface for higher bandwidth and redundancy.

Overview of Link Aggregation

Link aggregation allows multiple physical Ethernet ports on the OLT to be grouped into a logical interface, increasing bandwidth and providing backup links in case one port fails . This is especially important for uplinks to aggregation switches, ensuring stable and high-speed connectivity. The aggregation can be static (manual configuration) or dynamic using LACP (Link Aggregation Control Protocol), which automatically negotiates the active links between devices .

Key Configuration Considerations

1. Port Consistency: All member ports in the aggregation group must have consistent configurations, including:
   • Speed and duplex mode (full duplex required)
   • VLAN settings (PVID and permitted VLANs)
   • STP parameters (enable/disable, priority, cost)
   • Link type (trunk, hybrid, or access) for Layer 2 aggregation
2. Aggregation Modes:
   • Static (ON mode): Ports are manually added to a group; no LACP negotiation is required. Up to 8 ports can be aggregated .
   • Dynamic (Active/Passive LACP): Ports negotiate automatically using LACP. Active mode initiates negotiation, passive mode responds. Up to 12 ports can be in a dynamic group, with 8 active and 4 backup .
3. Member Port Selection: In LACP, a reference port is used to compare configurations. Only ports matching the reference port are selected to forward traffic; others remain unselected .

Steps to Connect OLT to Aggregation Switch

1. Identify Ports: Choose multiple uplink ports on the OLT and corresponding ports on the aggregation switch.
2. Configure Aggregation on OLT:
   • Create a link aggregation group (LAG) and assign member ports.
   • Set the aggregation mode (static or LACP dynamic).
   • Ensure all member ports have consistent speed, duplex, VLAN, and STP settings .
3. Configure Aggregation on Switch:
   • Mirror the aggregation group configuration on the aggregation switch.
   • If using LACP, ensure the switch ports are set to active or passive mode to match the OLT configuration .
4. Verify Connectivity:
   • Check that all selected member ports are forwarding traffic.
   • Monitor for backup ports in case of link failure.
   • Use CLI or EMS tools to confirm the LAG status and bandwidth aggregation .

Best Practices

• Use LACP dynamic aggregation for automatic failover and easier management.
• Keep port configurations synchronized to avoid unselected ports.
• Monitor the LAG for link failures and ensure backup ports are functional.
• Document the aggregation group IDs and member ports for maintenance and troubleshooting. By following these steps, the OLT can be reliably connected to the aggregation switch, providing increased bandwidth, redundancy, and stable network performance .