CH5: Managing a Cisco Internetwork

What do you need to do before backing up an IOS image to a network server on your intranet?

- Make sure you can access the network server - Ensure that the network server has adequate space for the code image - Verify the file naming and path requirement

What do you need to verify before attempting to copy an IOS image to or from a router if you have a laptop or workstation's Ethernet port directly connected to the router's Ethernet interface?

- TFTP server software must be running on the administrator's workstation - The Ethernet connection between the router and the workstation must be made with a crossover cable - The workstation must be on the same subnet as the router's Ethernet interface - The "copy flash tftp" command must be supplied the IP address of the workstation if you are copying from the router flash - If you're copying "into" flash, you need to verify that there's enough room in flash memory to accommodate the file to be copied

What are the main reasons you would want to change the configuration register?

- To force the system into the ROM monitor mode - To select a boot source and default boot filename - To enable or disable the Break function - To control broadcast addresses - To set the console terminal baud rate - To load operating software from ROM - To enable booting from a TFTP server

What are the main steps to password recovery?

1. Boot the router and interrupt the boot sequence by performing a break, which wil take the router into ROM monitor mode 2. Change the configuration register to turn on bit 6 (with the value 0x2142) 3. Reload the router 4. Enter privileged mode 5. Copy the startup-config file to running-config 6. Change the password 7. Reset the configuration register to the default value 8. Save the router configuration (and reload the router)

What is the default order of an IOS loading from a router?

1. Flash 2. TFTP Server 3. ROM

What are the Four Steps of the Router Boot Sequence?

1. The router performs a POST, testing the hardware to verify that all components of the device are operational and present 2. The bootstrap then looks for and loads the Cisco IOS software 3. The IOS software looks for a valid configuartion file stored in NVRAM 4. If a startup-config file is in NVRAM, the router will copy this file and place it in RAM and call the file running-config. The router will use this file to run the router.

How many bits is the configuration register and what form is it in?

16 bits, 2 bytes, or 4 nibbles. It's in hexadecimal

What is a way to play with the boot order and avoid upgrading the IOS of routers individually?

Boot all your routers from a TFTP host. This unfortunately creates a single point of failure, so it's not necessarily recommended.

What is the Mini-IOS component of a Cisco router?

Called the RXBOOT or bootloader by Cisco, the Mini-IOS is a small IOS in ROM that can be used to bring up an interface and load a Cisco IOS into flash memory. The Mini-IOS can also perform a few other maintenance operations.

What is the Flash Memory component of a Cisco router?

Flash Memory stores the Cisco IOS by default. It is not erased when the router is reloaded. It is EEPROM (electronically erasable programmable read-only memory) created by Intel.

What does IOS stand for?

Internetwork Operating System

If you use the "show version" command, what line shows the total amount of flash that is present?

It's the line at the bottom. - 62720K bytes of ATA CompactFlash (Read/Write)

What is the NVRAM component of a Cisco router?

NVRAM (Nonvolatile RAM) is used to hold the router and switch configuration. NVRAM is not erased when the router or switch is reloaded. It also doesn't store an IOS. The configuration register is stored in NVRAM.

What is the RAM component of a Cisco router?

RAM (Random Access Memory) is used to hold packet buffers, ARP cache, routing tables, and also the software and data structures that allow the router to function. Running-config is stored in RAM, and most routers expand the IOS from flash into RAM upon boot.

What is the ROM component of a Cisco router?

ROM (Read-Only Memory) is used to start and maintain the router. It holds the POST and the bootstrap program, as well as the Mini-IOS.

What is the POST component of a Cisco router?

Stored in the microcode of the ROM, the POST (Power-On Self-Test) is used to check the basic functionality of the router hardware and determine which interfaces are present.

What is the ROM Monitor component of a Cisco router?

Stored in the microcode of the ROM, the ROM monitor is used for manufacturing, testing, and troubleshooting.

What is the Bootstrap component of a Cisco router?

Stored in the microcode of the ROM, the bootstrap is used to bring a router up during initialization. It will boot the router and then load the IOS.

What is the Configuration Register component of a Cisco router?

The Configuration Register is used to control how the router boots up. This value can be found as the last line of the "show version" command output and by default is set to 0x2102, which tells the router to load the IOS from flash memory as well as to load the configuration from NVRAM.

What is ping and what does it do?

The Packet Internet Groper (Ping) utility is used to test network connectivity

What is the default configuration register and what does it tell the router to do?

The default configuration setting is 0x2102 and it tells the router to look in NVRAM for the boot sequence

If there's not enough room for both the old and new image you want to load, what will happen?

The old image will be erased!

What bit of the configuration register is used to ignore the NVRAM contents and conduct password recovery?

The sixth bit

What do you need to make sure of when you are using TFTP to move a file?

You need to make sure the TFTP server has a default directory specified or it won't work. TFTP is just a "grab it and place it" program in this situation.