Appendix D Configuration Register Information

Configuration Bit Meanings

Bit 8

Bit 8 controls the console Break key. Setting bit 8 (the factory default) causes the processor to ignore the console Break key. Clearing bit 8 causes the processor to interpret Break as a command to force the system into the bootstrap monitor, halting normal operation. A Break can be sent in the first sixty seconds while the system reboots, regardless of the configuration settings.

Bit 10 and Bit 14

Bit 10 controls the host portion of the Internet IP broadcast address. Setting bit 10 causes the processor to use all zeros; clearing bit 10 (the factory default) causes the processor to use all ones. B it 10 interacts with bit 14, which controls the network and subnet portions of the IP broadcast address. Table D-4shows the combined effect of bit 10 and bit 14.

Table D-4 Bit 10 and Bit 14 Settings

Bit 14

Bit 10

IP Address (<net> <host>)

 

 

 

Off

Off

<ones><ones>

 

 

 

Off

On

<zeros><zeros>

 

 

 

On

On

<net><zeros>

 

 

 

On

Off

<net><ones>

 

 

 

Bit 11 and Bit 12

Bit 11 and Bit 12 in the configuration register determine the baud rate of the console terminal. Table D-5shows the bit settings for the four available baud rates. (The factory set default baud rate is 9600.)

Table D-5 Bit 11 and Bit 12 Settings

Baud

Bit 12

Bit 11

 

 

 

9600

0

0

 

 

 

4800

0

1

 

 

 

2400

1

1

 

 

 

1200

1

0

 

 

 

Bit 13

Bit 13 determines the server response to a bootload failure. If boot commands are in the configuration file, the router software processes each boot command in sequence until the process is successful or the end of the list is reached. If the end of the list is reached without a file being successfully booted, the router will retry the netboot commands up to six times if bit 13 of the configuration register is set, otherwise it will load the operating system software available in ROMmon. If bit 13 is not set, the router will continue to netboot images indefinitely. The default setting for bit 13 is 0. If bit 13 is set, the system boots the boot helper image found in boot flash memory without any retries.

 

Cisco 7401ASR Installation and Configuration Guide

D-4

OL-5419-01 B0

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Cisco Systems 7401ASR manual Bit 10 and Bit, Bit 11 and Bit, Bit IP Address net host, Baud Bit