The choice of manual or auto provisioned SDPs has limited impact on the amount of required provisioning. Most of the savings are achieved through the automatic instantiation of the pseudowire infrastructure (SDP bindings). This is achieved for every auto-discovered VSIs through the use of the pseudowire template concept. Each VPLS service that uses BGP AD contains the ‟pw-template-binding” option defining specific Layer 2 VPN parameters. This command references a ‟pw-template” which defines the pseudowire parameters. The same ‟pwtemplate” may be referenced by multiple VPLS services. As a result, changes to these pseudowire templates have to be treated with great care as they may impact many customers at the same time.
The Nokia implementation provides for safe handling of pseudowire templates. Changes to the pseudowire templates are not automatically propagated. Tools are provided to evaluate and distribute the changes. The following command is used to distribute changes to a ‟pw-template” at the service level to one or all services that use that template.
tools perform service id 300 eval-pw-template 1 allow-service-impact
If the service ID is omitted, then all services are updated. The type of change made to the ‟pwtemplate” influences how the service is impacted:
Adding or removing a split-horizon-group causes the router to destroy the original object and recreate using the new value.
Changing parameters in the vc-type {ether | vlan} command requires LDP to resignal the labels.
Both of these changes affect the services. Other changes are not service affected.