Description
In CCVPN use case, if a customer wants to set up a VPN from Beijing to London, we can use ONAP to stretch such a VPN service that is cross operator, cross domain and cross layer. Customer can also create a multi-site to multi-site service, as well as delete or add a site on the existing service according to their demands.
We abstract the VPN service topology into three kinds of nodes: Site, SOTN VPN Infra, SD-WAN VPN Infra. The composition of Sites and SOTN VPN Infras can comprise a SOTN VPN Service, the composition of Sites and SD-WAN Infras can comprise a SD-WAN VPN Service, while the combination of these three nodes can make up a SOTN+SD-WAN VPN Service.
All the sites and VPN Infras needs a set of inputs. In Casablanca release, SDC is not capable to support multiple sets of inputs in one service template so that we have to design the sites and VPN infra as a service and use 3 service templates to describe each kinds of node. The CCVPN service is created by mean of separate multiple Service Orders , with one service orderItem for each of the services that makes up the CCVPN connectivity Service.
Such solution, on the one hand, obviously, violates the idea of using one service template to create a CCVPN service. A CCVPN service consists of several site service and VPN service which in fact should be resource; On the other hand, Customers couldn't choose which site or VPN Infra to be included when instantiating a real service because all these resources are regarded as a service.
Requirements
- Modeling team accept a multiple node design in service template (Anatoly Katzman )
- SDC supports input List structure in TOSCA service template (Ofir Sonsino )
- SO support List input interface(Seshu Kumar Mudiganti )
The ideal solution should be that a CCVPN service can be instantiated by using one service template and customers can decide the number of resources when creating a service.
TOSCA working group also pays attention to this problem and they came up with an improved service templates which can satisfy our needs:
Keyname | Required | Type | Constraints | Description |
occurrences | no | range of integer | when not specified, defaults to [1,1] | The optional minimum and maximum number of instances that can be created from this node template. If not specified, only one single instance can be created. |
instance_count | no | integer | when not specified, defaults to the lower bound of the range specified by the ‘occurrences’ keyname | The requested number of runtime instance of the node template.
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see Reference:
TOSCA Enhancements to Support Multiple Node Template Instances