Install guide

1-4 Release Note

Software Version 2.7.5

C613-10454-00 REV A

For example, if a router has two ports A and B, and:

• port A is configured with a weighting factor of 1000

• port B is configured with a weighting factor of 2000.

then the load balancer is twice as likely to select port B than port A. However, if

both ports are assigned the same weighting factor then the selection process

resorts to the round robin selection method.

Weighted Least Connect Distribution

This distribution method assigns new load balancer sessions to WAN ports

based on the current load (in sessions) on each WAN port. The load on a port is

determined by dividing the number of its current sessions, by its weighted

value. The WAN load balancer selects the WAN port with the smallest load, or

more precisely, the port with the least connections relative to its weighting. To

simplify configuration, weighted least connect uses the inverse of these values

then selects the port with the highest numeric value. This is explained in the

following example.

If a router has two ports A and B, and:

• port A is configured with a weighting factor of 4000 and has 10 current

WAN load balancer sessions

• port B is configured with a weighting factor of 2000 and has 4 current

WAN load balancer sessions

then the weighted least connect for port A will be, 4000 ÷ 10 = 400, and the

weighted least connect for port B will be 2000 ÷ 4 = 500.

In this case, the load balancer will select port B next because it has the higher

weighted least connect value.

Because the weighted least connect method is based on dynamic information,

it offers a slight advantage over the static ratio assignment method used by the

weighted lottery selection. In the weighted lottery configuration, distribution

of WAN load balancer sessions could become slightly unbalanced if some of

the WAN ports are unavailable for selection, or if some WAN load balancer

sessions persist for longer than others. By contrast, the weighted least connect

configuration would maintain an even session distribution.