Don’t take your eye off GTP en route to 5G

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Published February 27, 2018

Changes to the European Union’s roaming regulations and raised awareness of security risks are fueling dramatic increases in GPRS Tunneling Protocol (GTP) traffic.

Everywhere you look, pressure is intensifying on service providers to scale and secure their networks. GTP is not a historical relic yet, and is still shaping the evolutional direction and eventual functionality of 5G. Harness it correctly and consumer expectations for quality of service will be met. Drop the ball and you’ll soon be in trouble.

Easy as GTP

As ever, service providers are locked in a race to satisfy increasingly data-hungry consumers while maintaining network performance. More than ever before, this is creating a need to correlate GTP control and data traffic on a per-subscriber level.

Essentially, GTP is a network protocol that enables packet networks to signal and carry data between devices and applications. Originally GTP was used for GPRS (so-called 2.5G) networks. Today, accelerating GTP tunnels and offloading GTP data traffic is critical to the performance of 3G and 4G networks, as well as Internet of Things (IoT) and M2M traffic management and load balancing in the core network.

GTP is also used between other nodes, including Voice-over-WiFi-related evolved Packet Data Gateway (ePDG) scenarios. In addition, it is the basis for the emerging Packet Forwarding Control Plane (PFCP), a 5G-focused protocol.

Security challenges

Recently, the GSMA has raised awareness of security vulnerabilities as the native GTP protocol lacks strong, built-in security mechanisms. Various protocols have been investigated by the GSMA Fraud Security groupand the resulting FS.20 document (entitled GTP Security) currently acts as guideline for GSMA members.

Common GTP security issues include confidential data disclosures, denial of service, network overloads, and a range of fraud activities. Prevention depends on circumstance but, as a minimum, solutions that provide full traffic visibility and an all-encompassing DDoS protection should be in place.

Smart routing

Another key challenge is to effectively route and distinguish between GTP traffic. A subscriber’s traffic will differ wildly from that destined for mobile virtual network operators (MVNO) or a network slice dedicated to IoT. Charting a course for GTP traffic is usually based on the content of GTP messages (GTP Information Elements) and also – but not limited to – other aspects like source and destination. A smart GTP routing function can select the right Packet Gateway (PGW) or network slice that best suits a specific service. 

Fortunately, existing technology is capable of harnessing advanced routing, proxy, and security functionalities while being able to access GTP Information Elements. F5, for example, can tap into over 100 types of these including APN, IP address, MS-ISDN, RAT Type, PDN Type (v4/v6), user location info, aggregate max bit rate, and quality of service. If, say, a terminal wants web access, it can select the Internet APN, which is conveyed via GTP. It then allows the network to select the right, or best available, PGW to route the traffic towards the Internet. It is also possible to support various GTP Proxy cases such as routing MVNO and a service provider’s own traffic to different destinations using the same APN.

GTP is going nowhere, and it is vital that service providers grasp how to optimize its capabilities in both the present and the imminent era of 5G. It is a cutthroat industry out there. Customers don’t hang around for long if services fall short and their traffic is delayed.

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