WT-474: Introducing Subscriber Session Steering and dynamic subscriber placement

WT-474: Introducing Subscriber Session Steering and dynamic subscriber placement

By Jonathan Newton, Principal Network Architect at Vodafone’s Fixed Access Centre of Excellence

Traditional fixed broadband networks, typically, have relatively static configurations in the access network, with subscribers mapped to specific service gateways. This static mapping restricts a service provider’s ability to offer innovative edge services, and requires pre-planning and modelling to ensure that the network is loaded evenly and can effectively cope with device failures. Essentially, it is an inefficient and time-expensive process for service providers and limits service innovation.

That’s why the Broadband Forum is working on WT-474. WT-474 will deliver an open standards approach to the architecture and data models to enable a network capability for flexible and dynamic real-time decisions about the placement of individual subscribers. This core principle is called Subscriber Session Steering.

What is Subscriber Session Steering?

The ability to deliver flexible, on-demand connectivity that detects traffic changes and automatically scale to preserve the user experience can help drastically improve a service provider’s offering. It is achieved by utilizing service aware dynamic ‘session steering’, as demonstrated at the latest Broadband World Forum event. These specifications enable operators to unlock new revenue-generating services.

Subscriber Session Steering delivers a more flexible access network – allowing dynamic service-aware placement of subscriber sessions and load balancing of sessions across the available service gateways.

Individual subscribers can be mapped dynamically to the service gateway that can meet their application performance needs.

What’s the benefit?

For the end user, it means on-demand access to low latency services, improved availability, reduced impact of maintenance, and for the CSP, it will result in improved network load balancing, an easier route to right-size the network, and an improved upgrade process for new software and services.

For example, if a network is not meeting the quality required for a user’s video streaming or gaming, Subscriber Session Steering can dynamically change it to a different Broadband Network Gateway (BNG) in real-time.

How does it help the service provider’s business?

Session steering will provide a policy-based approach for subscribers to be placed into specified network slices. This enables business benefits for fixed customers, including new opportunities for specific vertical market segments, enterprise customers, wholesale customers, and mobile backhaul/front-haul.

Dynamic steering will also allow the network to dynamically redistribute subscriber load across the network (by selecting specific user plane, and network paths), allowing operators to better utilize network assets. Extending the network balancing will allow subscribers to be automatically redistributed in the case of a BNG User Plane Failure. This will reduce the number of dedicated standby BNG nodes, in turn reducing costs and/or improving customer availability.

Until we are able to steer sessions, virtual BNG (vBNG) deployments will remain statically tied to specific servers, without the ability to scale effectively. A true cloud vBNG is capable of scaling up and down to meet demand, adding and removing virtual BNG user plane elements seamlessly. A session Steering function can allow load balancing across vBNG user plane instances. This will allow operators to save energy and ensure their networks can run at a higher load.

The increasing cadence of new software deployments to the network is not possible in today’s software deployment approach where a BNG element needs to be upgraded or rolled back in its entirety. Session steering will allow operators to manage software in a cloud native model, rolling out software in a controlled way, upgrading on a subscriber group, or even on a per subscriber basis. This is critical to being able to enable new functionality and fix network issues or bugs more rapidly.

The ability to treat different subscribers separately will allow operators to use different network paths for subscribers with varying service offerings. This means that we can apply greater resilience to subscribers with higher service offerings, and more generally ensure that the we can reduce network costs to ensure efficient and cost effective services for our customers. This will both reduce back-haul costs as well as giving better competitive effectiveness in the market, offering a greater range of service levels with the knowledge that the network costs can match the service offering.

Watch the Broadband Forum Subscriber Session Steering demo in full here: https://www.broadband-forum.org/bbf-wt-474-subscriber-session-steering-demo-2.