Weighted Fair Queuing (WFQ) is a packet scheduling technique allowing guaranteed bandwidth services. The purpose of WFQ is to let several sessions share the same link. WFQ is an approximation of Generalized Processor Sharing (GPS) which, as the name suggest, is a generalization of Processor Sharing (PS) [6]. In PS each session has a separate FIFO queue. At any given time the N active sessions (the ones with non-empty queues) are serviced simultaneously, each at a rate of 1/N:th of the link speed. Contrary to PS, GPS allows different sessions to have different service shares. GPS have several nice properties. Since each session has its own queue, an ill-behaved session (who are sending a lot of data) will only punish itself and not other sessions. Further, GPS allows sessions to have different guaranteed bandwidths allocated to them. In [7] Parekh showed that when using a network with GPS switches and a session that is leaky bucket constrained an end-to-end delay bound can be guaranteed.