After a packet is sent to the outgoing interface on a router, it is queued for transmission on the physical media. The amount of time a packet is queued on the router is determined by the availability of the outgoing physical media as well as the amount of traffic using the interface.
J-series Services Routers support queues 0 through 7. If you configure more than eight queues on a Services Router, the commit operation fails and the router displays a detailed message stating the total number of queues available.