In some examples, an example method to provide an IPsec anti-replay window with quality of service (QoS) at a first network endpoint may include configuring a multiple number of anti-replay windows, generating a first security association (SA), and establishing the first SA with a second network endpoint. The first SA may include a first multiple number of security parameter indexes (SPIs), where each of the first multiple number of SPIs may be assigned to a specific QoS level, and each of the first multiple number of SPIs may be assigned to one of the multiple number of anti-replay windows. Establishing the first SA with the second network endpoint may include assigning the first SA to a first encryption key, and providing the first encryption key to the second network endpoint.