An Automatically Switched Optical Network (ASON) is a dynamic signaling-based network via a distributed control plane that provides auto-discovery and dynamic connection setup. This enables improved support for end-to-end provisioning, re-routing and restoration, new transport services such as bandwidth on demand, rapid service restoration for disaster recovery, and switch connection within a private network. ASON enables support for a wide range of narrowband and broadband client's signals (e.g., SDH/SONET, IP, Ethernet, ATM, Frame Relay, ESCON, FICON, Audio/Video).
ASON routing architecture is a network that is subdivided based on operator decision and criteria (e.g., geography, administration, and/or technology). The network subdivisions are defined in ASON as Routing Areas (RAs) or domains. The routing architecture and protocols applied after the network is subdivided are operator's choice. A multi-level hierarchy of RAs provides for a hierarchical relationship of RAs based on containment (i.e., child RAs are always contained within a parent RA). The hierarchical containment relationship of RAs provides for routing information abstraction, thereby enabling scalable routing information representation. Within an ASON domain and for each level of the routing hierarchy, multiple routing paradigms (hierarchical, step-by-step, source-based), centralized or distributed path computation, and multiple different routing protocols may be supported. The architecture does not assume a one-to-one correspondence between a routing protocol and an RA level, and allows the routing protocol(s) used within different RAs (including child and parent RAs) to be different. The routing adjacency topology and transport topology are not assumed to be congruent. The requirements support architectural evolution, such as change in the number of RA levels, as well as aggregation and segmentation of RAs.
The description of the ASON routing architecture provides for conceptual reference architectures, with definition of functional components and common information elements to enable end-to-end routing in the case of protocol heterogeneity and facilitate management of ASON networks. Various telecommunication companies have shown interest in building their networks using domains, wherein a domain is considered to be any collection of network elements within a common sphere of address management or path computation responsibility. The domains are built upon the ASON model where internal network to network interfaces (I-NM) are used within a domain or RA, and external network to network interfaces (E-NNI) are used to connect domains or RAs. Routing Controllers (RCs) are used to exchange topology information between domains, which may be as full or abstracted topologies. There are primary RCs and any number of nodes may be assigned as backup RCs (BRCS), usually there is only one backup RC per RA. PCEs (Path Computation Engines) may be used in conjunction with the RCs to provide path computation across multi-domains. In this disclosure, it is assumed that an RC function encompasses the function of a PCE as well. The RCs are initially manually configured by the operator and the IP addresses of the RCs in the other RAs are manually configured by the operator, referred to as the remote RCs.
Each network element within the domain is configured with the Node_ID of the RC and the Node_ID of the backup RC(s). This method is used to define a domain (i.e. the nodes associated with a particular RC belong to the same domain). By knowing the RC in the domain, each network element informs the RC of the Transport Network Assigned (TNA) address it supports via a message, which allows the RC to know all the TNAs reachable within its RA. This information is then shared with the other RA across the E-NNI either in a full or summarized fashion.
Manual splitting and manual merging of RAs within a network is known in the art. This known method for a manual reconfiguration one node at a time, may be traffic affecting. The manual method is time intensive and error prone. There is not an automatic and efficient method that enables a carrier to reconfigure RAs by merging two at a time or splitting one into two. In addition, the IETF or ITU-T standards have not standardized the splitting and merging of domains. Although the ITU-T has noted the problem and identified possible actions that can be performed, no method for the automatic merging or splitting of domains has been suggested.