Impact of Denial of Service Solutions onNetwork Quality of Service

The Internet has become a universal communication network tool. It has evolved from a platform that supportsbest-effort traffic to one that now carries different traffic types including those involving continuous media withQuality of Service (QoS) requirements. As more services are delivered over the Internet, we face increasing riskto their availability given that malicious attacks on those Internet services continue to increase. Several networkshave witnessed Denial of Service (DoS) and Distributed Denial of Service (DDoS) attacks over the past few yearswhich have disrupted QoS of network services, thereby violating the Service Level Agreement (SLA) between theclient and the Internet Service Provider (ISP). Hence DoS or DDoS attacks are major threats to network QoS. Inthis paper we survey techniques and solutions that have been deployed to thwart DoS and DDoS attacks and weevaluate them in terms of their impact on network QoS for Internet services. We also present vulnerabilities thatcan be exploited for QoS protocols and also affect QoS if exploited. In addition, we also highlight challenges thatstill need to be addressed to achieve end-to-end QoS with recently proposed DoS/DDoS solutions.