a. The resource and the location costs.
b. The transport cost.
c. The dynamic cost.
d. The distance factor.
e. Load balancing value.
This is the base cost associated to the resource and the base cost associated to the location.
3.2.2. The transport cost
When a call transport is needed, this cost is the one to ensure traffic between the locations.
3.2.3. The dynamic cost
This is a virtual cost used to decrease the priority of a media server presenting an abnormal behavior. By abnormal behavior, we consider congestions, no response (at all) to new calls, improper response, etc. Each time the suspicious behavior is detected, the dynamic cost is increased by one, causing the media server to be avoided for next calls.
3.2.4. The distance factor
This value is a distance computation between the destination address and the media server address. For example, the distance factor between sip:1234@1.2.3.4 and media server at 1.2.3.1 will be smaller that the distance between the same destination and the media server at 1.2.4.1.
3.2.5. Load balancing value
When load balancing is activated (see next section, “resourcesLoadBalanced” ), the computed value added to the cost will become bigger as the fill factor of the resource is getting close to its limits. For example, the “load balancing value” include in the computation will be bigger for a media server already handling 25 calls on a maximum of 30 calls than for a media server handling 2 calls on a maximum of 30 calls. This value is not absolute. For example, the computation for a media server handling 25 calls on a maximum of 30 will give the same result as for a media server handling 250 calls on a maximum of 300.
The maximum number of lines taken into account in the calculus is the outbound one if specified. If not the total limit is used. If no limit at all is included, 9999 is used
4. Required settings in Sip.config
4.1. allowDynamicCost
This attribute defines if dynamic costs must be computed and included in computations. This attribute’s default value is “true”.
4.2. dynamicCostResetInterval
This attribute defines when dynamic costs are reset. As seen in previous sections, dynamic cost is incremented when a “failure” occurs on a media server. This can lead to a permanent exclusion if no failure is detected on other media servers. In order to give a chance to the suspicious media server to be included in selection list, the dynamic costs are reset at regular interval. This attribute defines the duration (in seconds) of this interval. This attribute’s default value is “3600”, meaning one hour.
4.3. resourcesLoadBalanced
This attribute defines if load balancing must be applied on the system. This attribute’s default value is “false”.
4.4. resourcesLoadBalancingIncludesInbound
This attribute defines if inbound calls must be included in load balancing computation. This attribute’s default value is “false”.