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Link aggregation modes and what they do for you
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01/03/2013- Most of the 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.

Load Balance

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


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.


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.


(Exclusive OR) This mode dedicates one port for each destination address. XOR provides load balancing and fault tolerance.


(Adaptive Transmit Load Balancing) Using this mode, no special switch is required to perform link aggregation. The outgoing traffic is distributed according to the current load on each connection. Incoming traffic is received by the current connection. If the receiving connection fails, another connection takes over.


(Adaptive Load Balancing) Includes balance-TLB plus receive load balancing (RLB) for IPV4 (Internet Protocol version 4) traffic. This mode also doesn't require any special switch support. The receive load balancing is achieved by ARP negotiation. The bonding driver intercepts the ARP Replies sent by the local system on their way out and overwrites the source hardware address with the unique hardware address of one of the connection in the bond such that different peers use different hardware addresses for the server.


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.

As you can see, every mode has its own purpose which provides different advantages. If you use link aggregation with your Thecus® NAS, make sure it's set-up with the mode that fits you best.

About Thecus®
Established in 2004, Thecus Technology Corp provides market leading network attached storage and network video recorder solutions, committed to revolutionize how everyone from home user to enterprise level business centrally stores, manages and accesses their digital data both onsite and cloud-based. Thecus strives to deliver continuous innovation through cutting edge technology and design to provide data storage with the most customer-friendly platform, rapid performance and robust security. In May 2016, Thecus was formally acquired by Ennoconn Corporation and thus became part of the Foxconn IPC Technology group. Partnered together this diverse group of companies work in tandem to provide a total IoT (Internet of Things) solution. Now with an unparalleled portfolio to work with, Thecus is collaborating to bring unprecedented change to the network storage industry.