TransportPCE describes an application running on top of the OpenDaylight controller. Its primary functions are to create, modify or delete paths according to service requirements on OTN/WDM transmission networks. Path determination can be either performed within the application according to a set of metrics or can be provided by an external application (typically a planning tool). From an architecture point of view, this external application can either transmit directly the path to the controller or towards Transport PCE application. The second option avoids potential resource conflicts in case of nearly simultaneous path implementation requests from both applications on a dedicated link but requires an interface from this application to the external one. The implementation is left open for the time being. Thanks to the presence of OTN switches, path determination is multilayer by nature. Path creation, modification or deletion shall be performed with user-interface (UI) providing a global view of the network and simple UI dialogs for path management.
The nodes in the network are ROADMs and OTN switches. They run GMPLS with link-state routing protocols (e.g. OSPF-TE) to exchange topology, capabilities... The abstracted topology view and path setup dialogs conceptually enables TransportPCE to manage any connection-oriented network technology including Generalized MPLS (GMPLS) networks.
Topology recovery shall be performed in two ways. Network Management System conveys the link-state database through its own API (e.g. Corba or REST). Preferred option is the development of a dedicated IGP-TE plug-in in Opendaylight that is capable of listening IGP-TE link-state messages coming from a designated node. A plugin interface towards NMS shall be implemented only for legacy transport networks that can not activate GMPLS. Cases may appear where two subdomains managed by a single PCE are connected by another domain managed by another organization (still belonging to the same operator). It shall be therefore possible to model this interconnection link with some properties left intentionally empty (typically latency…) and TransportPCE shall be able to manage such links.
All nodes that are candidate path sources and sinks are configured with either a path computation element protocol (PCEP) session to the OpenDaylight PCEP plug-in or Netconf session to the Netconf plug-in. PCEP or Netconf is used to convey path create, modify and delete information between OpenDaylight and specific path end-point nodes. TransportPCE employs PCEP RESTCONF APIs to communicate desired path management actions to OpenDaylight which in turn are passed down via PCEP/Netconf to specific endpoint nodes. Endpoint nodes propagate path management actions through GMPLS (RSVP-TE) for path implementation. In case of legacy transport networks that can not run GMPLS, a plugin interface towards NMS shall be used instead in order to activate in all concerned nodes.
TransportPCE is implemented using the either DLUX UI or NeXt UI framework (to be decided). If path computation in electrical domain (OTN switching) does not raise unsolvable issues when confined to a limited set of metrics, path computation in optical domain is a much more complex topic and is strongly vendor-dependent. Therefore, the objective is to limit path computation to an agreed limited set of optical metrics that should be accessible from the abstracted network topology. The strategy of verifying the physical implementation of the path is left for further study (a first step will consist in listing the failure cases depending on abstracted topology view). It should also be possible for TransportPCE to consult with or import path computation results generated from external components.
Network resource management can become cumbersome and generate lengthy delays for implementation in the field especially when it involves IP, OTN and WDM layers. TransportPCE is an OpenDaylight application that aims to offer a simple, fast, user-friendly and automated way to see and manage paths traversing an OTN/WDM network through a DLUX/NeXt UI. Networks must become more and more agile in order to face the evolution of new services and SDN enabled WAN management is a necessity. Beyond the need for a more agile transmission network, WAN SDN management shall ultimately combine IP traffic engineering and connection management at OTN/WDM layer in order to optimize network resources.
TransportPCE is an application implemented in the DLUX/NeXt UI. It will communicate with the OpenDaylight controller across current and future model-driven RESTCONF APIs.
Potential changes needed in OpenDaylight to support TransportPCE are:
• implementation of an IGP-TE YANG model that in turn yield new RESTCONF APIs towards upper layers
• implementation of an IGP-TE plug-in
• implementation of NMS plug-in for topology acquisition if IGP-TE can not be activated (legacy transport networks)
• updates to PCEP-related YANG models that in turn yield new RESTCONF APIs towards upper layers
• updates to Netconf-related YANG models that in turn yield new RESTCONF APIs
Data requiring persistence will be handled within the TransportPCE application
Xavier Pougnard, Orange - email@example.com / XavierP
Guillaume Lambert, Orange - firstname.lastname@example.org
Patrice Robert, Orange - email@example.com
Johan Gustawsson, TeliaSonera - firstname.lastname@example.org
Martin Birk, AT&T - email@example.com
All contributed code will adhere to OpenDaylight's copyright and license policies.