The article explains how to set up Link Aggregation (LAG) on a switch, detailing the differences between Static LAG and LACP (Link Aggregation Control Protocol). LAG combines two or more ports to increase capacity and reliability. Static LAG requires manual configuration on both ends, while LACP allows automatic negotiation using control packets. The article outlines the benefits and drawbacks of each method, such as static LAG's lack of CPU load and LACP's ability to detect link failures. It provides a step-by-step guide on configuring LAG, including checking port status, ensuring loop guard is inactive, and setting up the link aggregation through the switch's settings menu.
What is Link Aggregation (LAG)?
Link Aggregation (LAG) is a technique that combines multiple network ports into a single logical link to increase overall bandwidth and enhance network reliability. This process can be implemented in two primary ways: Static Link Aggregation and Link Aggregation Control Protocol (LACP).
Static Link Aggregation
Static Link Aggregation involves manually configuring two or more ports to operate as a single logical channel. This setup requires careful configuration on both ends (e.g., switches or servers) to ensure that both sides of the link have identical static trunk configurations. The result is a logical port that provides a combined bandwidth that is the sum of the individual ports.
Benefits of Static Link Aggregation:
- Groups two to eight ports as a single virtual link, enhancing throughput.
- Increases network reliability and redundancy between connected devices.
Link Aggregation Control Protocol (LACP)
LACP is a standardized protocol defined in the IEEE 802.3ad specification. It allows for the automatic bundling of multiple physical ports into a single logical link, using LACP packets to manage the connection.
With LACP, several ports are connected to form a Link Aggregation Group (LAG) with bandwidth equal to the sum of the aggregated ports. The protocol not only automates the negotiation process for port aggregation but also includes mechanisms to monitor the link's health. In the event of a line failure, LACP can automatically remove the faulty line from the aggregation, ensuring continued operation.
Benefits of LACP:
- Enables automatic negotiation between switches by sending LACP packets.
- Monitors line integrity to detect failures, even if the failure is not directly connected to the LAG, and can remove malfunctioning links from the group.
- Maximizes available bandwidth utilization between switches and other network devices.
- Facilitates load balancing across multiple ports, optimizing overall network performance.
Conclusion
Link Aggregation is a vital technique for enhancing network capacity and reliability. Whether through static configurations or the more dynamic LACP, combining multiple ports into a single logical link effectively improves data throughput and resilience against individual port failures. As networks continue to evolve, understanding and implementing LAG can significantly bolster network performance and reliability.
| Type | Static Trunk | LACP |
| Mechanism | Static binding without packets negotiation | Dynamically negotiated by LACP packets |
| Pros | No CPU loading | Detect link failure without any physical link down |
| Cons | Cannot detect link failure | Higher CPU loading due to controlling packets |
Configure Link Aggregation (LAG)
NOTE: First configure, then connect!
Check before you start
Check the following:
- Check Port Status, here Example Port 7/8:
Also, make sure that the ports are enabled:
Next, check that the Loop guard is not active on these Ports. Navigate to:
SWITCHING > Loop Guard
Then hit "Apply"
Check that Port Security is disabled on needed Ports by navigating to:
SECURITY > Port Security
So now we can start to configure Link Aggregation.
Link Aggregation
So now we can start to configure Link Aggregation by navigating to:
PORT > Link Aggregation > Link Aggregation Setting
Activate the Group ID that you want to use and select the same Group at the ports you want to aggregate.
Info: src-dst-mac to distribute traffic based on a combination of the packet’s source and destination MAC addresses.
Select Ports which should be used by (here) T4:
Go down and apply the settings.
Now Port 7/8 is bound together to a Link Aggregation.
Don’t forget to save the configuration: Switch Configuration Lost After Power Outage or Power Cycle Issue
Verify Results
You can double-check, go back to Status:
And you can see Trunk is assign to Port 7&8 and ready to use.