A wide range of emerging networking applications demand computer networks to provide Quality of Service (QoS). Packet switches play one of the most crucial roles in computer communication systems and traffic control in packet switches is the key to QoS provisioning. The Combined Input and Cross-point Queuing (CICQ) switch is a newly developed switch architecture that employs the crossbar-based switching fabric and a variant of the Combined Input and Output Queuing scheme with distributed output buffer at each crosspoint. The CICQ switch is being widely deployed in computer networks, therefore how to control traffic in a CICQ switch to provide QoS guarantees becomes an important issue. In this paper, we investigate the QoS performance of a variety of traffic control algorithms applied in CICQ switches. Since it is well known that the OQ switch is an ideal case that provides the optimal QoS performance, we compare the achievable performance of the CICQ switch under each packet scheduling policy with the performance that can be achieved by an Output Queuing (OQ) switch with the same scheduling algorithm. The performance analysis in this paper is based on a simulation system that we develop using OPNET Modeler.