1 Components of a Cisco router
Cisco routers are composed of hardware and software. The hardware mainly includes the central processor, memory, interfaces, console ports and auxiliary ports, etc. The software is mainly the router's IOS operating system
1.1 Hardware components of Cisco routers
The functions of each components of a Cisco router are as follows:
(1) Central Processing Unit (CPU)
Cisco routers generally use the Motorola 68030 and Orion/R4600 processors. The CPU of the router is responsible for the configuration and management of the router as well as the forwarding and processing of data packets. The processing speed of the router's data packet depends on the CPU's processing speed to a large extent.
Cisco Routers use several different types of memory, each of which assists the router in different ways. These include the following four types of memory: read-only memory (ROM), flash memory (Flash), volatile RAM (NVRAM), and random memory (RAM).
each router's interface has its own name and number. The full name of an interface consists of its type and at least one number, and its number starts with the number 0. The router interface is used to connect the router to the network and can be divided into two types, LAN interface and WAN interface.
(4) Console port
The console port provides an EIA/TIA-232 asynchronous interrogation line interface for local configuration of the router.
(5) Auxiliary Port
The Auxiliary Port provides an EIA/TIA-232 asynchronous interface. It is usually used to connect to a Modem for remote management of the router
1.2 Cisco router operating system
Cisco routers rely on IOS (lnternetwork Operating Syetem), the soul of the Cisco device, which directs and coordinates the hardware of the Cisco device for the delivery of network services and applications. IOS is an operating system that is configured via the command line. By using IOS commands, a variety of configurations can be made for Cisco network devices, and make them have various network functions. For different models of Cisco devices, the IOS used differs due to their different hardware configurations.
2. How Cisco routers work
When a router receives a network layer datagram, it decides whether to forward it directly to the network to which it is connected, to another router, or to discard it. The router uses the source and destination address information at the network layer to determine which network to send the message to. And if the source and destination network numbers are in the same network, it will be sent to the specified host on that network. When a packet arrives at the router, joins in the queue, and then the router proceeds as follows, it extracts the packet's destination address, checks the routing table, and selects the best path if there are more than one path to the destination. In addition, the router takes various factors into accounts, such as the network load, latency, length of the packet and the type of service specified in the header of the packet on the Internet, when selecting the optimal path.
3. The basic model of Cisco IOS
There are four basic modes in Cisco's IOS command line mode:
3.1 User mode
A new router will see the "router>" prompt at the end of the boot process, which is the lowest level mode for accessing the router. At this point, the router is in user command mode and the user can see the connection status of the router and access other networks and hosts, but cannot see or change the settings of the router.
3.2 Privileged mode
Type enable at the router> prompt to put the router into the privileged command state router#, where you can see and change the router's settings. You can return from privileged mode to user mode by using the command disable or exit.
3.3 Global mode
Type “configure terminal” at the router# prompt to bring up the prompt router (config) #, at which point the router is in global setup mode and you can set the global parameters of the router.
The above is an introduction to the current Cisco router network technology. We truly believe that with the increasing number of Internet users and the construction of broadband networks in full swing, the demand for router technology updates will become increasingly strong. In the future, routers will be more advanced and a new generation of technologies that can better meet the requirements of network development will emerge in endlessly.
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