Mobile networks offer many opportunities for consolidation and efficiency. Expect a large amount of activity here, as the move to either an NFV or a converged platform for mobile can deliver functions including evolved packet core (EPC) and the multitude of IP-based Layers 4 through 7 functions known as the SGi/Gi-LAN.
Standardizing the Mobile Core
The mobile network has been built with a patchwork of specific functions, often implemented in specific hardware or software devices, sometimes on a series of proprietary platforms. One of the goals is to move these functions to a common platform for mobile, this platform could come in the form of a standardized NFV platform or some sort of converged, integrated hardware solution focusing on efficiency in the SGi/Gi-LAN
Why is this happening now? Over the years, the mobile core, as it’s known, has evolved from a hodgepodge of proprietary gear bridging legacy, analog mobile systems to the next-generation, packet-only network, which is based primarily on Internet Protocol (IP) packets. While this transition is never really finished, it’s clear that the the bulk of mobile voice and data traffic is becoming IP-centric over time, which means it makes more sense to handle this traffic in a unified way. The arrival of 4G, LTE, and the development of 5G – all of which are built around packet-based networking – means this trend will only increase over time.
Collapsing the Mobile Core
The arrival of the standardized mobile architecture has defined the shift to a primarily IP-based mobile network with elements defined by standards groups such as 3GPP. With the move to architectures such as the Evolved Packet Core (EPC), the core of the network becomes packet-based. EPC supports advanced, high-bandwidth services, such as LTE, that run both voice and data using packet-based networks.
According to 3GPP, one of the goals of EPC was to have a “flat architecture,” with fewer nodes handling packets to make it more efficient. It also separates the user data, or payload, from the signaling network, or control plane.
The decision to move primarily to – and the pursuit of a flat architecture – offers an opportunity for more layer 4-7 services to be executed together, using technologies and architectures from layer 4-7 solutions used in cloud data centers. Telecom operators see this as an opportunity to collapse both the hardware and software architectures to drive more efficiency out of their infrastructure.
Integrating Efficiency in the SGi/Gi-LAN
Of course, it’s not easy. Mobile networks are famously complex. In the EPC alone, there are myriad functions. These include the serving gateway (SGW), which connects to the access network; the packet gateway (PGW or sometimes PDN-GW), the interconnect between the EPC and the external IP networks; the mobility management entity (MME), which deals with the control plane and signaling; and the home subscriber server (HSS), which facilitates subscriber-related information.
The EPC is also connected to external, IP-based networks, which can include the IP multimedia subsystem (IMS), load balancers, firewalls, and other IP-based functions in the area that has become defined as the SGi/Gi-LAN, after the SG-interface. This is the access point between the P-GW and PDN (see diagram below). Think of it as “all IP functions connected to the EPC.”
You get the picture. There are myriad functions and services that can be configured to serve subscribers. And here’s where it gets interesting: Imagine that all these functions can be plugged into one platform as software – rather than requiring specific hardware or software installation devices for each function, as was the model in the legacy network. Then imagine that these services can be executed all at once.
There are several ways to do this, including using virtualization or dedicated hardware. Our readers and network users tell us that EPC and SGi/Gi-LAN functions such as firewalls and load balancing are prime candidates for virtualization – as revealed in our recent report, the 2016 “2016 Mega NFV Report Part II: VNFs – Downloads.”
Mobile operators have made their intentions clear with a number of proofs-of-concept (PoCs), especially those launched in the ETSI NFV group. For example, a team including Telenor, ConteXtream, SkyFire Networks, Guavus, and Red Hat proposed a subscriber-aware SDN solution in the Gi-LAN portion of the mobile network. This PoC uses an SDN-enabled switch to ensure that traffic flows for each subscriber are chained through available virtual or physical network functions. In another ETSI PoC known as “Full ISO 7-layer stack fulfilment, activation and orchestration of VNFs in carrier networks,” Telstra, Hewlett-Packard, Alcatel Lucent, and F5 Networks have demonstrated the potential for using NFV for orchestrating SGi/Gi-LAN functions.
A Single Converged Platform Approach
There are other approaches to efficiency in the SGi/GiLAN – including using a unified converged platform. It makes sense to combine multiple functions in one platform, particularly Layer 4-7 capabilities like CG-NAT, security, and load-balancing. Because this requires a detailed look inside the packets, combining the functions can reduce the latency and the overhead of touching packets multiple times (compared to service chaining which often requires opening up packets, inspecting and modifying them and them putting them back on the wire repeatedly)
While some operators will look at NFV, others may be looking for the highest possible performance today, which could be a converged, specialized, hardware-centric approach.
Regardless of whether unified hardware platforms or NFV is used to deliver the new converged mobile infrastructure, several key elements will have to be considered. These include:
- Cost efficiency – Don’t count out hardware yet, as the cost per bit to move, inspect, and transform packets could be cheaper, especially in a converged platform
- Manageability – NFV doesn’t imply manageability. There are more moving parts to coordinate, but balanced against more automation. Hardware platforms today have rich APIs for management and integration too. And in particular if most or all the L4-7 functions stem from a single vendor, there might be greater efficiency and more consistency in managing and troubleshooting.
And we’re also seeing many traditional hardware solution providers introduce virtualized or software-only versions of their product with similar functionality and management APIs. This provides a migration path for service providers who need the most cost-effective or highest performance today but need a NFV solution longer term. As we’ve documented, the move to new architectures is not a quick process. But it’s becoming clear from our research that mobile operators are drawn to the appeal of a unified platform for mobile network functionality, whether it’s taking a virtualized NFV or converged platform approach.