một số 32-bit được sử dụng để mặt nạ ra từng phần. Mặt nạ này thực hiện một hoạt động hợp lý, với địa chỉ IP. Bất cứ nơi nào mặt nạ là một trong nhị phân, nó được coi là phần mạng, khi mặt nạ được không, nó được coi là chủ nhà. | Upon receiving a packet cbus interface cards query the cbus controller for the destination line card. The cbus controller performs a local route-cache lookup for the destination if this is the first packet to the destination the cache lookup fails and the cbus controller sends a query to the CSC card for a route-table lookup. The CSC returns the result to the cbus controller which caches the result and responds to the query from the original line card. The receiving line card forwards the packet over the cbus to the appropriate destination line card and subsequent packets to the same destination can now be autonomously switched over the cbus without the intervention of the centralized CPU. This boosted the performance of the AGS platform to 80 000 pps. Within the AGS architecture interface buffers were maintained on the cbus controller and system buffers on the CSC 4 CPU card. Only four of the AGS chassis slots could be used for cbus interface cards. With the introduction of the 7000 and 7010 series Cisco maintained the same auxiliary-switching processor design paradigm but introduced a new range of processor cards. The extended Cisco bus included connectivity to every slot five slots in the case of the 7000 three slots in the case of the 7010. The switch processor performed an identical role as the cbus controller to offload fast-cache lookup from the CPU so that packets that had a cache hit could be forwarded autonomously and to perform the MAC layer-rewrite writing the new MAC header to the packet. Recognizing that the CPU was now predominantly used for route calculations Cisco renamed it the route processor and the auxiliary switching engine was renamed the switch processor. An alltime high of 200 000 pps was achieved on the 7000 router performing autonomous switching see Figure 5-5 . Figure 5-5. Cisco 7000 Architecture 100 One additional refinement took place on the 7000 series. The silicon switch processor also known as the silicon switch engine or SSE is a .
