VOO Extends Infrastructure Capacity with Granular 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, as well as mobile services primarily to residential customers in Wallonia and Brussels. The company has been one of the fastest growing service providers in Europe, currently serving around half a million subscribers.

The Challenge

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. VOO assumed their network was suffering cyber attacks, but had no visibility to confirm it. While frequent network capacity expansion alleviated the congestion temporarily, this was not a sustainable strategy for VOO as the costs involved where 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 also allow them to control it cost-effectively and in compliance with net neutrality guidelines.

Allot Solution

The first order of business was to deploy 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. 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 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 assured the customer experience.

VOO also activated Allot’s DDoS protection service which is fully integrated in Allot Service Gateway and found that the unpredictable service disruptions were indeed caused by massive Distributed Denial of Service attacks, in particular NTP and DNS amplification attacks, and UDP fragmented floods.

Once the Allot ServiceProtector 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 saturating network resources. Using Allot ServiceProtector, to surgically mitigate the attacks, VOO has freed up Gigabits of bandwidth. Most importantly, they have 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.

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


Discover the source of persistent network congestion and reduce it without frequent investment in additional infrastructure.


Deploy Allot Service Gateway Tera with fully integrated CMTS congestion management and DDoS protection provided by Allot ServiceProtector.


  • Delay infrastructure investment and reduce costs
  • Assure service availability
  • Maintain consistent quality of service
  • Enhance customer satisfaction