Support Systems: GMPLS - Unlocking the Potential of Intelligent Metro Optical Networks

The challenge is very clear. Now, more than ever, service provider profitability depends on improved use of network resources and increased time to market.

This means service providers that will take the lead as they emerge from the current weak climate are those that deploy the most efficient and cost-effective infrastructures. The metropolitan network, specifically, has become the focal point for service providers as they rethink their network strategies. With at least 60 percent of network costs associated with this network segment, service providers are looking to new technologies to build more efficient metro network architecture. One viable solution service providers can consider for their network strategy is the introduction of generalized multiprotocol label switching (GMPLS) -- a new generation protocol suite that can help service providers reduce operational expenditures and both increase their service offerings and the speed with which they deliver those services.

The New Network Dial Tone

Recognized as the 'dial tone' of the new generation optical network, GMPLS has rapidly emerged as a highly scalable routing and signaling protocol suite that unifies the traffic engineering, provisioning, bandwidth management and restoration of all service types.

GMPLS is a logical evolutionary advance from IP through MPLS. With support from the Internet Engineering Task Force (IETF) and the Optical Internetworking Forum (OIF), it has quickly emerged as a solution that service providers are now considering for their networks. Development of GMPLS began with the premise that it is possible to implement full integration of provisioning for all traffic types. This protocol therefore has been developed with the goal of creating a single suite of protocols that would be applicable to all service and transport traffic.

GMPLS brings the intelligence and dynamic circuit (or path) provisioning of packet services to TDM and wavelength services. Its extensions offer a common mechanism for data forwarding, signaling, and routing on transport networks. GMPLS thereby extends the MPLS label and label switched path (LSP) mechanisms to create generalized labels and generalized LSPs. These extensions affect routing and signaling protocols for activities such as label distribution, traffic engineering, and protection and restoration.

Unifying the Network

GMPLS is in many ways analogous to the labels used by courier delivery services. A single type of label, defined by its tracking number, is used for all packages and destinations. The same label is used to get a letter, a parcel or a suitcase delivered across town, country or ocean, and by the most appropriate means, be that bicycle, truck or air freight.

The single label guarantees the quality of service: speedy, cost-efficient delivery that can be read by the different departments, such as sorting, routing and delivery. Similarly, GMPLS provides a labeling mechanism that can be used to get all traffic types to their destination -- packet, TDM and wavelength. Thus, GMPLS enables evolution to simpler, more efficient network architectures.

A GMPLS network also offers substantial improvements in network efficiency and flexibility compared to current architectures. It allows each network layer to be managed according to its unique attributes and enables utilization of the inherent differences of the network layers to ensure optimal use of network resources. The following are areas where GMPLS promises significant improvements:

Provisioning: GMPLS provides an important economic impact by its ability to automate network resource management and the service provisioning of end-to-end traffic-engineered paths. Service provisioning has been a manual, time-consuming, and costly process, especially in traditional, voice-centric, SONET transport networks. To manually provision an end-to-end high-speed connection, a service provider must determine which SONET rings the connection traverses and then provision bandwidth on each ring. If any ring is at capacity, an alternative path or capacity upgrade must be planned and pre-provisioned before propagating the connection information to all sites. These time-consuming processes can take weeks and months. In contrast, GMPLS-based nodes allow service providers to automate the provisioning and management of the network and promise to lower the cost of operation. While it is too early to quantify the cost savings of GMPLS, industry reports indicate that with an intelligent optical mesh metro network a provider can save at least 70 percent of its operating costs and reduce service delivery time by 95 percent. This reduces service delivery time cycles from 22 days to one day (assuming an average of eight hours of work per day and 22 working days per month).

Traffic engineering: Effective traffic engineering is one of the keys to maximizing return on investment while improving service offerings. It is necessary for optimal network performance, and it enhances a service providers' ability to offer service level agreements. Implementation of GMPLS traffic engineering and optical extensions for routing and signaling protocols improve network efficiency. These protocols provide enhanced network information, intelligent path computation and common signaling to packet, TDM and wavelength services.

Protection and restoration: GMPLS enables significant savings through resource allocation. Though each layer of an overlay network is efficient for the specific type of traffic it carries, protection must be duplicated between layers. The service network has no information about the transport network and must therefore specifically request the desired level of protection across the transport network, often duplicating resource allocation.

In a GMPLS-enabled network, however, the communication barrier between services and transport is eliminated, and the required protection is established with minimum resources. Resources can thus be re-allocated and the savings passed on to customers.

New Services, New Revenue

New service offerings enabled by GMPLS mean new revenue opportunities for service providers.

Services with quality of service constraints that require large increments of bandwidth are extremely difficult to provision real-time in a layered network. The layer consolidation offered by a GMPLS-enabled architecture allows any combination of fine grain packet LSPs to coarse grain OC48 LSPs. Therefore, service providers deploying GMPLS networks in a consolidated network will be able to offer a customer, for example, an OC12 from New York to London in the morning and an OC48 from New York to San Francisco the same afternoon, while making optimal use of all network resources.

A GMPLS network also enables service providers to manage traffic across all layers. They can view all the network layers and efficiently allocate resources to the most appropriate layer, thereby tailoring differentiated services to their customers' varied and changing needs, while reducing costs through optimal resource usage.

GMPLS enables service providers to reap greater benefits through more comprehensive and flexible service level agreement offerings to customers. With resource allocation no longer restricted to a specific network layer, service providers have greater flexibility in designing and enforcing SLAs, which can be used to generate new revenue.

GMPLS offers service providers a vehicle to help them migrate their networks from the current complex and costly architectures to simpler, more efficient models. Service providers who deploy GMPLS will not only see significant savings through improved network efficiencies, but will be able to offer advanced, revenue rich services to existing and new customers.

Deployment Strategy

While it is clear GMPLS has the potential to address some of the biggest network challenges facing metro networks, the protocol is still in its emergent phase. Issues such as end-to-end multivendor interoperability, interfacing to existing operational support systems, and demonstrating the operational and economic impact of its deployment, must still be addressed. Even though GMPLS has emerged very quickly, leveraging the standards work and field experience of MPLS, more work is expected to continue among the IETF working groups. This is to tailor the protocol specifications to fully adapt GMPLS to the open and interoperable standards the industry requires. Therefore, service providers are likely to adopt GMPLS with a phase-in strategy -- initially deploying GMPLS in overlay or vendor-specific network segments and establishing semi-automated capabilities, then, subsequently, addressing multivendor interoperability to extend the GMPLS control plane on an end-to-end basis for full automation. It is anticipated that semi-automated network deployments are likely by the end of 2003 with wide-scale adoption occurring beyond 2004. It is certainly clear that early adopters of GMPLS-based automation will be rewarded with a substantial competitive edge over other service providers.

Sab Gosal is director of product marketing at Polaris Networks. He can be reached at sgosal@polarisnetworks.com.

Provisioning Traditional SONET network vs. Intelligent Optical Mesh
Source: Polaris Networks

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