The effects of various factors on the performances of edge routers are analyzed in details. The results show that the delay requirement of different class of services can be satisfied by controlling the relative maximum assembly delay. Large burst size variation may lead to unfair in channel assignment. The more the number of edge routers in the OBS networks is, the higher Burst loss rate is. Low burst loss rate and high efficient can be achieved by increasing the number of output channels while the total capacity is invariable. However, the effect is degraded with the increase of the number of edge routers in the OBS networks.