One of the challenges introduced by the rollout of LTE is the enormous increase in data traffic that gets transported across the mobile core network. Studies have shown that LTE users, in addition to enjoying higher bandwidths, also consume considerably more data than 3G users. These scalability challenges are forcing mobile operators to review their Gi LAN network architecture and how the value added services (VAS) infrastructure elements plug into that. Traditionally mobile operators have been steering traffic into their VAS platforms (e.g. video optimization, web optimization, transparent caching, parental control, etc.) in a very static way using policy based routing (PBR) as presented in the figure below.
The advantage of this traditional port-based steering approach is that it is relatively simple to manage and configure. The disadvantage however is that economically this model is difficult to maintain with the constant increase of data traffic in mobile core networks. The VAS platforms are among the most expensive data processing components in the entire network, so mobile operators are currently looking for ways to optimize the utilization of these platforms in their networks. In the current architecture each of these VAS platforms are receiving data for which they are not providing any value. As an example, the video optimizer platform will receive traffic that isn’t video (a lot of port 80 traffic is plain web traffic), plus the mobile operator may have use cases where some video streams don’t need to be optimized.
Instead of pushing all that decision logic into the different VAS systems, a better approach is to change the static port 80 steering logic into a more dynamic context-aware intelligent steering logic (please see figure below). This intelligent steering logic is able to take contextual decisions on a per flow or even on a per HTTP transaction basis about which VAS service(s) each flow or HTTP transaction needs to be forwarded to. Some flows may actually have to be passed through multiple VAS platforms which results in service chaining. The goal of this new architecture is to make optimum use of the VAS services that are deployed. The intelligent steering logic is fully controlled using operator defined business policies that can take inputs from a PCRF (subscriber-based steering logic), from Radius transactions (e.g. radio access type steering, device type steering, … ), from third party APIs (e.g. congestion based steering) and from the data packet content (e.g. content-based steering) all of which provide ‘context’ to the flow.
An example of a statically configured intelligent steering policy that applies to all traffic on the Gi LAN is shown below. The goal here is to bypass the video optimizers whenever the subscriber is connected to the LTE radio network. As soon as the subscriber falls back to 2G or 3G coverage, his video streams will be steered through the video optimization platform. This architecture allows the mobile operator to keep the network as it was functioning before for their 2G and 3G users, without having to pass through all the LTE traffic through the same VAS services if that is deemed to be unnecessary.
Another example which includes service chaining for some subscriber traffic flows is the following scenario. In this use case the mobile operator wishes to continue using traditional port 80 forwarding for all mobile traffic to a video optimization platform, while adding a parental control service which needs to be activated only for subscribers that have opted in to that service. A PCRF is used in this architecture to push down the subscribers’ traffic management policies into the intelligent steering device. User A has subscribed to a parental control service and therefore the PCRF will point to a service chaining policy that will steer that particular subscriber’s port 80 traffic to both video optimization and parental control platforms. User B on the other hand will only have his port 80 traffic steered through the video optimization VAS service.
There are many other use cases but the above examples clearly demonstrate the flexibility of having an intelligent traffic steering platform inline on the Gi LAN interface. Not only do these advanced steering policies help mobile operators to cost optimize the utilization of their VAS platforms, they also allow for a rapid introduction of new services without having to re-engineer the entire network. The intelligent steering platform takes a central role by managing, steering and orchestrating all traffic flows in the mobile packet core towards the VAS services infrastructure and helps to reduce the total cost of ownership of the Gi LAN architecture. In addition to intelligent traffic steering other functionalities that are typically present on the Gi LAN could be consolidated. But that’s the subject of another article.