ccna 200 301 training videos

ccna 200 301 training videos.routers typically load and use the Cisco I0S image. However, Cisco routers can use different OSes for performing some troubleshooting, recovering router passwords, and copying new I0S files to flash memory when the flash memory is accidentally deleted or crashed. Table 20-2 lists the two router operating systems other than IOS, along with some related information.Table 20-2 Comparing ROMMON and RxBoot Operating SystemsOperating Environment Common Name Storage Location PurposeROM Monitor ROMMON ROM Old and New RoutersBoot ROM RxBoot, Boot Helper ROM Only in older routersNote that for both OSes other than IOS, the latest generations of Cisco routers support only ROMMON, not RxBoot, so this book will not cover RxBoot further than the brief mention in Table 20-2. However, ROMMON plays an important role in the password recovery process as well as when the router itself is not working properly.Configuration RegistersNext, before discussing the boot process, a general look at the Cisco router's configuration registers is also needed.Before the router loads the I0S and reads the startup config, it needs to use the configuration registers to look for the configuration settings at boot time. The 16 bits (4 hexadecimal digits) in the configuration register set a number of different parameters. For example, the console runs at a default speed of 9600 bits/s, but its default speed is set based on several bits in the configuration register. By changing specific bits in the configuration registers, the console speed can be changed the next time the router boots.You can use the config-register global configuration command to set the configuration router. Engineers set different values for the configuration registers for different purposes, but as previously explained, the most common is to help them tell the router which IOS to load during the password recovery process.0 For example, the command config-register0x2100 sets the value to 2100 in hexadecimal, which causes the router to load ROMMONOS the next time it reloads, instead of not IOS.