What are C-Line services?

C-Line services

C-Line services connect two SAPs that can be defined on SONET/SDH, DS3/E3,T1/E1 ports or TDM channels. NSP supports the creation of C-Line services over IP networks. When a C-Line service is deployed, the selection of the endpoints automatically utilizes the requisite technology (MPLS or L0 WDM) tunnels.

It is possible for C-Line services to use service tunnels that were not created using NSP.

Note: Policies for service-to-tunnel binding dictate the rules associated with the service binding. If no service tunnel meets all the constraints, and this is a new C-Line service, a new service tunnel is created.

Other parameters of the C-Line service are obtained from the specific templates referenced in the abstract API definition. The service definition in the abstract API, the detailed configuration in the service templates, and other network and tunnel parameters form the complete service definition, which is represented in the normalized model for C-Line. Specific configurations based on the devices are then constructed and deployed using the NFM-P.

Note: The SAP-to-SAP C-Line services can be provisioned if different ports are used for each endpoint.

For C-Line creation, NSP supports the 7x50 and 7705 SAR NE types. Third-party vendor NEs are supported via MDM.

The C-Line service creation requires you to specify a type of VC (pseudowire). The options are:

SAToP T1 (unstructured DS1)
SAToP E1 (unstructured E1)
CESoPSN (structured)
CESoPSN CAS (structured with CAS)

You can use pre-configured channel groups or NSP can auto-create channel groups as part of service creation. When channel groups are auto-created, the channel group ID will be the first timeslot.

Note: The number of timeslots in the channel groups must match in order to create a C-Line using the channel groups. For unchannelized endpoints, specifying the timeslots is not required.

The following behavior applies to NFMP-mediated C-Lines:

If there is an existing channel group that uses the full set of specified timeslots, that channel group will be used for the C-Line endpoints.
If the existing channel group is used by an existing service, the validation fails with a warning that the channel group is already being used by an existing service.
If a channel group with all the specified timeslots does not exist, a new channel group with the specified timeslots will be configured.
When configuring a new channel group, if one or more timeslots are already being used by other channel groups, validation fails with a warning saying that the timeslot is being used by another channel group.
If the C-Line reuses existing channel groups, and if the channel group ID is not the first timeslot, a validation error is not triggered and NSP will use that channel group regardless.
If the channel group parameters configured on the endpoint of the C-Line do not match those on the existing channel group, NSP will change the parameters of the channel group to match what is specified on the C-Line endpoint.
If a C-Line service that was created using NSP is deleted, NSP will delete the channel groups that are in use.

Brownfield C-Line services

C-Line services created within NFM-P can be managed by NSP. In order for NSP to discover these services, their "NSD-managed” flag must be enabled within NFM-P. Once discovered by NSP, these services function the same way as C-Line services created within NSP, provided that they meet NSP requirements. Any change made to these services within NFM-P after discovery is propagated to NSP if the change impacts the topology of the service.

Note: The C-Line services created within NFM-P have an “Auto-delete” flag. When enabled, services without service sites are automatically deleted. This flag must not be enabled on services managed by NSP, as the “NSD-managed” flag is disabled upon service deletion, and remains so even if the service is recreated and resynchronized in NSP.

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