1.2 Introduction to WAN router
Router is a special computer, a router has the basic components are the same as desktop PCs, routers have the CPU, memory, system bus, and many interface input / output. Routers are designed to perform specific tasks that are not owned by the PC desktop. For example, the router connects and allows communication between two networks and determine the data path through the network connection.
Same with the PC, the router operating system needs to perform its function, namely Internetwork Operating System (IOS) software to run its configuration files. These configurations contain commands and parameters that control the flow of traffic into and out of the router. Routers use routing protocols to determine the best path.
The main components of the router is the random-access memory (RAM), nonvolatile random-access memory (NVRAM), flash memory, read-only memory (ROM) and interfaces.
RAM has the functions and characteristics as follows:
- Save the routing table
- Handling the ARP cache
- Dealing with fast-switching cache
- Handles packet buffering and share RAM
- Handling the queue package
- Provide temporary memory for configuration files when the router works
- Data will be lost when the router is switched off or restart
NVRAM has functions and characteristics as follows:
- Provides storage for the startup configuration file
- Data is still there even though the router is turned off or restart
Flash memory has the functions and characteristics as follows:
- Handling the IOS image
- Providing access to software updates without having to remove the chip on the processor
- Data is still there when the router is turned off or restart
- Can store multiple versions of Cisco IOS software
- It is the kind of Electrically Erasable Programmable Read-only memory (EEPROM)Router is a special computer, a router has the basic components are the same as desktop PCs, routers have the CPU, memory, system bus, and many interface input / output. Routers are designed to perform specific tasks that are not owned by the PC desktop. For example, the router connects and allows communication between two networks and determine the data path through the network connection.
Same with the PC, the router operating system needs to perform its function, namely Internetwork Operating System (IOS) software to run its configuration files. These configurations contain commands and parameters that control the flow of traffic into and out of the router. Routers use routing protocols to determine the best path.
The main components of the router is the random-access memory (RAM), nonvolatile random-access memory (NVRAM), flash memory, read-only memory (ROM) and interfaces.
RAM has the functions and characteristics as follows:
- Save the routing table
- Handling the ARP cache
- Dealing with fast-switching cache
- Handles packet buffering and share RAM
- Handling the queue package
- Provide temporary memory for configuration files when the router works
- Data will be lost when the router is switched off or restart
NVRAM has functions and characteristics as follows:
- Provides storage for the startup configuration file
- Data is still there even though the router is turned off or restart
Flash memory has the functions and characteristics as follows:
- Handling the IOS image
- Providing access to software updates without having to remove the chip on the processor
- Data is still there when the router is turned off or restart
- Can store multiple versions of Cisco IOS software
ROM has the functions and characteristics as follows:
- Handles the commands for power-on diagnostic selt test (POST)
- Save bootstap programs and basic operating system
- Need a chip off the motherboard when you upgrade the software
Interface has the functions and characteristics as follows:
- Connect the router to a network as data packets turnover
- Just being in the motherboard or as a separate module
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