Features and architecture of Cisco Routers

Source: Internet
Author: User

Understanding the features and architecture of Cisco routers the basic knowledge of Cisco routers is still important for a network engineer, which is the foundation of Cisco technology. This document describes the features and architecture of a Cisco Router Based on a Cisco router. Before learning about the various troubleshooting and diagnostic tools available for Cisco routers, it is important to understand the basic architecture of Cisco routers. Network engineers should understand the role of diagnostic command execution and the impact on router performance. Switching and routing are frequently used in network interconnection. The exchange mentioned here is completely different from the frame-level exchange in the LAN: 1. The exchange process refers to how the router transmits packets between two different interfaces. For example, a Cisco router receives a packet at Ethernet interface 0. 2. the router first obtains the MAC header information from the message, and then checks the packet header at the network layer. 3. Check whether the route table matches the destination address of the packet. Assume that the route table contains matching items and the next hop address is another vro. The vro1 can be reached through Ethernet interface 1. Then the router needs to check the second-layer address of the next hop. If the IP address does not exist, an ARP broadcast packet must be sent on the Ethernet interface 1. If no ARP response is received, the router discards the packet. If there is a response, the router establishes an Ethernet frame to the next hop router. In this example, the entire process from receiving an Ethernet frame to establishing and sending an Ethernet frame is called the switching process. Note that the ARP parsing process is generally not considered as part of the exchange process. In the above process, the route table query is executed to find the next hop address, which indicates that the exchange process is used. This is the simplest packet exchange method, so it has a large overhead and latency. All routing protocols ultimately depend on the establishment of the route table. The router updates the corresponding route table by receiving the route update packets sent from neighboring Routers running the same protocol. This is called the routing process ), it is mainly completed by the route processor. Currently, www.2cto.com is widely used in Cisco routers in China, including the 2500 series, 4000 Series, 7000 Series, and 7500 series. These routers perform similar routing processes, however, the exchange process varies according to the system structure. The 7000 Series supports process switching, fast switching, autonomous switching, and Silicon Switching. The Cisco7500 series routers have improved the architecture of the 7000 Series. The functions of the Route Processor and exchange processor are integrated into the router exchange processor (RSP. This new architecture reduces the load on the system bus during fast switching. The integrated functions optimize the performance, stability, scalability, and security of both the Route Processor and switch processor. Vrouters of the 7500 series do not support autonomous switching or Silicon Switching, and support more flexible optimization and switching. The hardware structure of Cisco4000/2500 series routers is simpler than that of 7000/7500 series routers. These devices share the memory only during the SWAp process. All the message caches and caches are in the shared storage. Therefore, they only support fast switching or process switching. The exchange process needs to query the route table to make route selection, and other exchange technologies increase the switching speed through caching, because their cache locations are different and called different technologies.

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