As ISP’s and Telco’s converge towards all-IP network infrastructures, the problem of QoS becomes more acute. To address it, operators are deploying differentiated services based on DiffServ where different types of traffic will get different priorities and therefore different QoS. In this paper, we investigate to what extent DiffServ can provide service protection against failures. We compare this scheme with another protection model that we call DiffProtect, based on differentiated optical protection. The results show that the priority traffic is equally well protected by both techniques. The conclusions are more complex for medium priority traffic where the distributions of delay and jitter change with the failure probability. Both methods can protect this traffic reasonably well but the DiffProtect technique can keep a bound on the delay better than the DiffServ method.