Ports on an aggregation switch are typically divided between access-layer connections and uplinks to core switches, often including high-speed SFP+/QSFP ports for aggregation and redundancy.

Physical Port Layout

Aggregation switches consolidate traffic from multiple access switches and forward it to the core layer. The ports are generally organized as follows:

• Access Layer Ports: These are usually 10/1-GbE or 10/40-GbE SFP+ ports that connect to access switches, wireless access points, or servers. They handle the bulk of traffic coming from the edge of the network .
• Uplink/Core Ports: High-speed ports such as 40-GbE QSFP+ or 100-GbE QSFP28 are reserved for uplinks to core switches or for interconnecting aggregation switches in an MC-LAG setup. These ports provide redundancy and high throughput .
• Port Aggregation Ports: Multiple physical ports can be grouped into a logical link using static aggregation or LACP (Link Aggregation Control Protocol). Aggregated ports are often sequentially numbered and must share the same speed, duplex, and VLAN configuration .

Port Aggregation Considerations

• Static Aggregation: Ports are manually bound into a logical channel. All ports must be up and have identical VLAN attributes to function correctly .
• Dynamic Aggregation (LACP): Ports negotiate automatically with the remote device. Modes include active (initiates negotiation) and passive (responds only). Only ports in the active band forward traffic, while backup ports take over if a primary link fails .
• Sequential Port Requirement: Aggregated ports are typically sequential in numbering to simplify configuration and ensure proper load balancing .

Example Configuration on a FortiSwitch Aggregation Layer

A typical aggregation switch, such as the FS-1048E, may have:

• 48x GbE/10-GbE SFP+ ports for access-layer connections.
• 6x 40-GbE QSFP+ or 4x 100-GbE QSFP28 ports for uplinks to core switches or MC-LAG interconnects.
• Ports are grouped in pairs or blocks for redundancy, with dual hot-swappable power supplies and redundant fans recommended for reliability .

Summary

In practice, the ports on an aggregation switch are physically labeled and grouped to distinguish between access connections and uplinks. Aggregation ports are configured either statically or dynamically using LACP, ensuring load balancing, redundancy, and failover. High-speed uplink ports are reserved for core connectivity, while the remaining ports handle traffic from access switches and edge devices . Proper configuration ensures efficient traffic flow and network scalability.