Cubro Blog

GTP Load Balancing in Hardware with EXA32100

Challenges in today's 3G/4G LTE Networks

A report from Gartner states that communications service provider (CSP) network infrastructure is undergoing a radical transformation with the adoption of emerging technologies. Infrastructure and operations leaders must make crucial lifecycle decisions to drive this transformation forward and optimise costs and benefits to end users.

The challenge in today's environment is the vast amount of growing data and the limited performance of existing probes. By deploying Cubro's network performance monitoring and diagnostics (NPMD) technology to monitor network demand and manage the capacity planning, the CSP can get the advantage of better functionality and advanced features. However, to cope with the increasing network traffic, it is vital to look at the network architecture holistically and strike a cost-effective balance which does not compromise on high performance.

For the probe to deliver the expected output, the data session should always be on the same probe, even when the mobile is moving in the network. The CSP has two options to manage the unprecedented traffic. One option is to use several probes to capture all the traffic. This can cost a massive amount of money. In addition to being a more expensive solution, it also requires the probes to be interconnected to share the captured information from different users and to get an overview of all data transferred in the network from the user equipment. One probe should know everything about a data session. If you look for a certain subscriber and experience of using the network; all sessions of this subscriber should be on the same probe. This requires the different probes in different locations to be connected to each other.

Another challenge is that a data session is typically open "forever" or for a very long time. As a result, typical approaches where the session is handled by TEID in the GTP protocol is not very useful because it needs a long time to get all TEID information. This is due to the reason that only when the session is established or updated, this information is transferred. 

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In addition to this, the third big issue is that on LTE networks the S5/S8 interface between S-GW and P-GW is typically not accessible because these two network elements are physical on the device. This means that only the S1U interface can be used. However, on this interface, the TEID is changed when the user is moving to a different tower, and it is nearly impossible to handle this. (See image 1)

It is a complicated matter because in order to follow the inter eNB handover, the full mobility management traffic (MME) must be analysed in real-time and this would be extremely expensive.


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Technical Solution

The Cubro solution is to load balance based on the inner user IP. The Cubro Sessionmaster EXA32100 assures that all messages belonging to a specific session are correlated before forwarding it to the probe. Since this function is done in hardware, multiple 100 Gbit traffic is possible with one unit. This cost-effective solution load balances and filters traffic in full line rate before sending it to the probe and as a result increases the monitoring tool efficiency.


  • Reduce cost by scaling the monitoring as traffic grows
  • Boost performance of monitoring probes
  • Increase the utilisation of monitoring tools by preventing system overload

Additional resources:

GTP Load Balancing

Sessionmaster EXA32100 

Case Study: Massive two-tier load-balancing soluti...
Packet slicing in 100 Gbit line rate


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Monday, 25 June 2018