VOO, Belgium

Success Stories


Service Provider


DDoS Protection & Congestion Management





“By keeping DDoS traffic off the network and managing CMTS congestion precisely where it occurs, we have been able to delay infrastructure expansion by 2 years and to save millions”

Tamara Leemans, VOO CTO


  • Cable connectivity is highly vulnerable to congestion
  • Lack of visibility into the network prevented optimization
  • Infrastructure expansion was not a sustainable strategy due to high cost


By deploying the Allot Service Gateway Tera, VOO was able to see their network traffic at a granular level and pinpoint the P2P traffic that was monopolizing the bandwidth. VOO was then able to enforce a subscriber QoS policy in real-time using our innovative congestion management solution. Allot DDoS Secure was able to free up additional Gigabits of bandwidth.


  • Delay and reduce infrastructure investment costs
  • Maintain consistent QoS by managing bandwidth usage at a granular level
  • Gain full visibility of DDoS attacks and valuable threat intelligence

VOO Extends Infrastructure Capacity via Congestion Management and DDoS Protection


About VOO

VOO is the leading provider of broadband cable services in southern Belgium. VOO delivers digital TV, telephony, and high-speed Internet service at 50, 100 or 150 Mbps. The Belgian service provider also delivers mobile services, primarily to residential customers in Wallonia and Brussels. VOO has been one of the fastest growing service providers in Europe, currently serving around half a million subscribers.



VOO’s growth trajectory and ability to attract new customers and keep them, depends on the operator’s ability to deliver non-stop access with consistently good quality of service. As a shared media, cable connectivity is highly vulnerable to congestion. VOO’s fast expansion was challenged by frequent and unpredictable episodes of congestion mainly on upstream channels which have limited capacity and could not accommodate the bandwidth demand. While preliminary investigation led VOO to suspect P2P traffic as the main cause of the recurring congestion, the operator was lacking the network visibility to validate this assumption. In addition, some congestion episodes were so extreme, they completely disabled service delivery, impacting tens of thousands of customers. While frequent network capacity expansion alleviated the congestion temporarily, this was not a sustainable strategy for VOO as the costs involved were very high and the relief was short-lived. Instead, they needed a more comprehensive solution that could pinpoint the cause of the congestion and where it was coming from and allow them to control it cost-effectively, in compliance with net neutrality guidelines.



The first order of business was to deploy the Allot Service Gateway Tera at a critical access-aggregation junction in the network, giving VOO full visibility of network traffic per CMTS channel or bonding group. As illustrated below, VOO manages CMTS congestion management policy as well as the DDoS Protection service provided by Allot DDoS Secure, which is embedded in every Allot Service Gateway. As a result, VOO can see and manage all traffic on the network at a very granular level, all from a central vantage point. Instead of controlling CMTS policy based on IP subnets, which can affect an entire residential neighborhood, VOO can enforce QoS policy on a discrete saturated node(s) that affects only one street in the neighborhood.


The granular traffic visibility provided by Allot showed VOO that 10% of CMTS upstream bonding groups were congested and confirmed that the culprit was P2P traffic which consumed 80-90% of the upstream bandwidth. VOO used Allot’s innovative CMTS congestion management solution (Smart Traffic QoE) to monitor traffic per CMTS channel or bonding group, to detect congestion per CMTS element according to predefined thresholds, and to enforce subscriber QoS policy in real-time with the same granularity. By managing the bandwidth utilization of P2P applications, VOO was able to reduce congested bonding groups from 10% to 1% almost immediately, which freed up bandwidth for other services and delivered higher QoE for end-users.


VOO also activated Allot’s DDoS protection service (DDoS Secure), which is fully integrated in the Allot Service Gateway. The activation revealed that the unpredictable service disruptions were indeed caused by massive Distributed Denial of Service attacks.


Once the Allot DDoS Secure sensor was activated, VOO saw that their network often sustained 20-40 cyber-attacks per day, with volumes reaching 60 Gbps per attack, and completely saturated network resources. Using Allot DDoS Secure to surgically mitigate the attacks, VOO has freed up Gigabits of bandwidth and eliminated service outages. Today, real-time alerts notify VOO when a threat is detected and when it has been mitigated.


Detailed attack-mitigation logs, event analytics, and trend/distribution reports support VOO’s network planning, threat management and operational decisions, while Allot’s unified management console monitors network and user activity and manages threat protection across the operator’s entire network. As a result, VOO is now recognized as the best performing network for delivering Netflix video content in their region.



By deploying Allot Service Gateway with fully integrated CMTS Congestion Management and DDoS Protection services, VOO can:

  • Free up available bandwidth on the upstream and postpone investment in infrastructure expansion by 2 years!
  • Neutralize DDoS flooding attacks automatically, before they affect network performance
  • Maintain consistently good quality of experience across the entire network
  • Comply with net neutrality by managing congestion precisely where and when it occurs
  • Extend infrastructure lifetime with more accurate investment schedules
  • Reduce the complexity and time spent on CMTS congestion management

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