Network slicing has attracted interest because it enables service providers to create customized virtual networks within one physical infrastructure. While slicing can be implemented using different technologies at different layers of the transport network, there are many advantages to using Optical Transport Network (OTN) technology to create the slices. OTN provides a service-level agreement (SLA)-aware solution with powerful tools that allow service providers to offer premium wholesale and business services with flexibility, security and guaranteed performance. With OTN, service providers can slice optical network capacity using different quality of service (QoS) parameters such as data speed, latency, priority and reliability to adhere to SLAs.

Benefits of OTN slicing

Today’s service providers need networks that can quickly adapt to changing traffic patterns. OTN slicing enables efficient and flexible network resource allocation, allowing service providers to deliver a wide range of services tailored to specific business requirements. By dividing the network into smaller, independent slices with dedicated resources, OTN slicing allows businesses to enjoy seamless, uninterrupted service experiences.

One of the key drivers behind service providers’ adoption of OTN slicing is the need for fast time to market. OTN slicing accelerates service provisioning with a highly agile and programmable Software-Defined Networking (SDN) infrastructure that helps providers launch services swiftly to capitalize on new opportunities. Network slice resources are dynamically added, changed or deleted to accommodate the requirements of the service mix.

OTN slicing is designed to avoid disrupting existing services. With the ability to allocate resources independently for each slice, service providers can introduce new services while ensuring the continued performance and reliability of existing offerings. This seamless integration makes it easy to enhance their service portfolios.

Service providers can also save with OTN slicing. By allocating resources on demand and sharing infrastructure, they can optimize resource utilization and reduce deployment costs. They can then pass the savings on to customers in industries such as healthcare, finance and manufacturing, allowing them to allocate their budgets strategically and invest in other critical areas of growth.

OTN slicing allows service providers to generate new revenue with customized services that use different transport network configurations to support a wide-ranging pool of SLAs and network KPIs. By tailoring network slices to the unique requirements of businesses, providers can deliver services that enhance customer satisfaction and unlock additional revenue streams.

OTN slicing: An enabler of business and wholesale services

There are several scenarios where OTN-enabled slicing can benefit service providers that offer wholesale or retail business services.

Multi-service slicing

Imagine a service provider that meets the needs of multiple customers with connectivity services such as residential broadband, 4G/5G and enterprise private lines (left pane of Figure 1). The provider can transparently transport these services over the same physical optical network using high-speed connections that support different interfaces, including Ethernet, SDH/SONET, OTN and Fiber Channel.

To ensure optimal performance, the service provider assigns each service to a specific transport slice based on its QoS requirements. By using OTN slicing, the service provider can better customize the services and bring them to market quicker. The services can groom and aggregate traffic to maximize resource utilization.

Figure 1: OTN-enabled network slicing examples

Customer-managed slice

Service providers may need to serve end customers that require dedicated network functions or performance but don’t want to manage the optical network. These customers may want a slice that creates a tailored solution for their business and gives them limited control over the management of the slice. For example, power utilities can be given an OTN slice that supports smart grid applications such as SCADA, teleprotection and CCTV, as shown in Figure 1. The slice can be divided into slices that address the network performance requirements of the different applications.

Multi-tenant slicing

Wholesale providers can also take advantage of OTN slicing. For example, a wholesale provider may have multiple local fixed/wireless provider tenants that lease wholesale connectivity services to avoid having to build out their own networks. Each slice must be isolated to avoid interference that could adversely affect its performance. OTN provides granular TDM time slots (in increments of 1.25 Gbps tributaries as in the case of ODUflex) to isolate individual services so that they adhere to underlying SLA performance requirements. These time slots are considered a hard isolation method because they are implemented using independent, circuit-switched connections that dedicate and reserve capacity for the individual slices.

For each tenant, the transport slices can be further divided and offered to end customers (Figure 1). Tenants typically require full control over the operation and maintenance of their own network slices—for example, to flexibly allocate or schedule resources based on changing customer service requirements. By using OTN slicing, the service provider can give the end business more control and flexibility.

5G transport slicing

To ensure long-term financial viability, 5G networks must support a wide range of revenue-generating services. These include enhanced mobile broadband (eMBB), ultra-reliable low latency communication (URLLC), and massive machine-type communication (mMTC) services that require different levels of network performance. To support these services, 5G networks must be adaptable, dynamic and programmable from end to end.

Slices across the end-to-end network are facilitated through close coordination and orchestration across the RAN, transport and core components using controllers in each domain. A transport slice may form the end-to-end slice using several technologies, including IP/MPLS VPNs, Ethernet VLANs, TDM timeslots and wavelengths. For services traversing the optical network, the end-to-end slice may consist of multiple OTN slices that are stitched together. In this case, OTN slicing allows mobile network operators (MNOs) to offer a far broader range of communication services that will provide ongoing revenue streams beyond simple connectivity and capacity.

Hard and soft slicing

For each of the scenarios described above, it can be advantageous to mix hard and soft slicing using different isolation methods. Table 1 compares the two methods. It shows that hard isolation guarantees performance by giving each slice dedicated resources and separating traffic in a concrete way to ensure that slices don’t interfere with one another. It also shows that soft slicing provides no limitations in bandwidth granularity and improves bandwidth efficiency through statistical muxing gains.

Table 1: Hard versus soft slicing

A hybrid hard and soft slicing approach gives service providers the best of both worlds, and could enable them to support mission-critical networks or meet regulatory requirements.. For example, providers can isolate traffic slices from each other using a combination of Layer 2 switching for soft isolation and Layer 1 OTN for hard isolation within the same optical data unit (ODU). This allows highly bandwidth-efficient soft slices to be contained within the hard slices, enabling guaranteed performance and an inherent high level of security from dedicated connections.

In multi-service networks, service providers must implement the required level of isolation to meet the QoS demands of the service mix. They must also have the tools needed to monitor and protect each service, all while maximizing bandwidth efficiency.

Addressing service diversity with the Nokia 1830 PSS

Part of the Nokia optical product portfolio, the 1830 Photonic Service Switch (PSS) is designed to address the challenges of multi-service networks that undergo changes in service types and traffic patterns over time. It offers multi-tier, elastic bandwidth adjustment in support of Layer 1 and Layer 2 services.

The 1830 PSS provides a packet and OTN solution that supports hard and soft isolation to make networks more flexible and efficient. It supports soft isolation by segregating traffic into different Layer 2 Ethernet virtual connections (EVCs), and hard isolation by separating traffic into different ODUflex channels with a granularity of 1.25 Gbps.

With the 1830 PSS, service providers have the freedom to optimize bandwidth utilization by allocating the line bandwidth between soft and hard isolated traffic. The 1830 PSS also supports standardized OTN mappings for various clients, including Ethernet, SONET/SDH, Fiber Channel and OTN, ensuring compatibility and preserving client timing, especially crucial in 4G/5G networks. It reduces OPEX by using SDN automation to enable the network to self-adjust to traffic changes.

For more information, please refer to our Hard-soft traffic isolation in transport networks white paper or visit the 1830 PSS and 1830 PSS-x web pages.