WAN Load Balancing on the Linksys LRT224

WAN Load Balancing is the capability to efficiently distribute traffic across multiple wide area networks (WAN).  By making use of multiple WAN links through load balancing, aggregate bandwidth capacity and network reliability are increased for the local area network (LAN).  This article will explain how WAN load balancing works on the Linksys LRT224 Dual WAN Business Gigabit VPN Router.

The Load Balance Algorithm is based on session.  A session is used to decide which WAN interface the traffic is distributed to.  To determine whether sessions are the same or not, the following elements are considered:
  • Source IP
  • Source port
  • Destination IP
  • Destination port
If these elements in two frames are similar, they will be regarded as the same session.  Traffic of the same session will go out on the same chosen WAN port.  Nonetheless, if any of the elements are different from the other, it is considered a different session.  The router will assign different sessions to different WANs, which is based on the WAN Bandwidth Ratio settings.

The WAN Bandwidth Ratio can be configured when you log in to the web-based setup page of your Linksys LRT224.  Go to Configuration > System Management > Bandwidth Management to set the maximum upstream bandwidth, maximum downstream bandwidth, and Quality of Service (QoS) rules.  The default bandwidth ratio of WAN1:WAN2 is 1:1.

The ratio of WAN1 upstream bandwidth and WAN2 upstream bandwidth is used by the Load Balance Algorithm to dispatch traffic.  The downstream ratio is not related to the load balance.  This is because the direction of load balance is controlled by the upstream LAN to WAN.

Example:  If the WAN1 upstream is 100000 and the WAN2 upstream is 50000, the load balance (session-based) ratio is 100000:50000 or 2:1.

The values of maximum upstream and maximum downstream are used to limit bandwidth only if you configure a QoS rule.

There are two ways to configure a QoS rule under the BANDWIDTH MANAGEMENT TYPE section:  by Min. Rate or Max. Rate.  During configuration, make sure to set the Type to Rate Control.  The minimum rate guarantees minimum available bandwidth, while the maximum rate restricts maximum available bandwidth.  Both values should not go beyond the maximum bandwidth provided by your internet service provider (ISP).

Also, the network route is prioritized over the load balance.  For example, if the WAN1 IP address is while the WAN2 IP address is and the Server1 IP is, all the traffic sent from the LAN to Server1 will pass through WAN1 without considering the Load Balance Algorithm.  This is because the WAN1 and Server1 both belong to the same network.

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