Link Aggregation

What is Link Aggregation

Majority of Thecus® NAS offer seven modes of LAG (link aggregation). Load balance, Failover, 802.3ad, Balance-XOR, Balance-TLB, Broadcast and Balance-ALB.

What is LAG?

LAG is used to bond multiple links between your NAS and your switch into one bigger and faster link, increasing the network capacity while maintaining a fast transmission speed without changing any hardware devices, thus reducing cost. Doing so will offer optimal resource utilization, maximize throughput, minimize response time, and avoid overload. LAG also provides redundancy, fault tolerance or load balancing.

Because every user has different needs and resources, many modes are available. Let’s have a closer look at the ones a Thecus® NAS can support.


Why? When you don’t have a 10Gigabit network card, and frequently access more than 1Gigabit speeds for larger audio and video files, using Link Aggregation technology could expand network bandwidth. Thecus NAS provides Link Aggregation, and allows you to set Jumbo Frame (1500~9000 bytes) and aggregation type. The following describes the significance of these settings and supporting measures.




Aggregation type:

Load Balance: This LAG balances outgoing traffic across the active ports and accepts incoming traffic from any active port.

When to use?

  • – The network service “constant line” demand can be used.
  • -When you have many small packets, you might also consider using, for example, when you use eMule/BT to download.
  • -MountNAS iSCSI LUN or a network drive to access video file editing work.
  • -When flow balance is required, cannot use Failover only.
  • -Different speed NIC can be shared, but not recommended.

Failover: LAG in failover mode uses a main port for incoming and outgoing traffic between the two devices while the others are kept as backup. If the main fails, the other one immediately takes the charge. No special switch is required to support this. This mode provides fault tolerance.

802.3ad: This mode requires a switch which can also support 802.3ad. This LAG mode uses the bandwidth of all available similar ports, sharing the transmission evenly.

Balance-XOR: This mode dedicates one port for each destination address. XOR provides load balancing and fault tolerance.

Broadcast: This mode uses all available ports to transmit the data towards the switch. If one port fails to transmit, the other ports assure the communication is completed, thus providing fault tolerance.

Balance-TLB (Transmit Load Balance): This mode for packet sends and receives job-production of different mechanisms. For the send port with automatic load balancing and fault tolerance, and receive port only with fault-tolerant features, this mode does not switch to support and setting.

Balance-ALB (Adaptive Load Balance): Send and receive at the same time with automatic load balancing and fault tolerance, when the failure of one network port, still operational sustainability; this mode does not switch to support and setting.

How to set up the client-side system’s NIC?

If you want to set up Jumbo Frame, you must first make sure that the network environment such as router / hub / switch specifications is supported. Even on the network, various client devices (PC/printer)have to support Jumbo Frame as well. For example, if a NAS set up to 9000 bytes Jumbo Frame, but the switch or PC does is not supported; this will cause packet restriction on receiving devices which are not supported, and will cause network bottlenecks at the router.

We’ll describe Jumbo Frame in the next article.


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