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confreg parameters

I referenced my confreg examples from

http://www.cisco.com/en/US/products/hw/routers/ps133/products_tech_note09186a008022493f.shtml

My question is, why is 0x2102 the default if you can easily use 0x3922 instead?

The benefit being that your console serial speed is 12 times faster.

Is there more to the confreg values than is written in the guide?

Configuration Register Setting Router Behavior
0x102
  • Ignores break
  • 9600 console baud
0x1202
  • 1200 baud rate
0x2101
  • Boots into bootstrap
  • Ignores break
  • Boots into ROM if initial boot fails
  • 9600 console baud rate
0x2102
  • Ignores break
  • Boots into ROM if initial boot fails
  • 9600 console baud rate default value for most platforms
0x2120
  • Boots into ROMmon
  • 19200 console speed
0x2122
  • Ignores break
  • Boots into ROM if initial boot fails
  • 19200 console baud rate
0x2124
  • NetBoot
  • Ignores break
  • Boots into ROM if initial boot fails
  • 19200 console speed
0x2142
  • Ignores break
  • Boots into ROM if initial boot fails
  • 9600 console baud rate
  • Ignores the contents of Non-Volatile RAM (NVRAM) (ignores configuration)
0x2902
  • Ignores break
  • Boots into ROM if initial boot fails
  • 4800 console baud rate
0x2922
  • Ignores break
  • Boots into ROM if initial boot fails
  • 38400 console baud rate
0x3122
  • Ignores break
  • Boots into ROM if initial boot fails
  • 57600 console baud rate
0x3902
  • Ignores break
  • Boots into ROM if initial boot fails
  • 2400 console baud rate
0x3922
  • Ignores break
  • Boots into ROM if initial boot fails
  • 115200 console baud rate

If the value you have for the configuration register is not in  the table, then determine which bits are set in order to compute the  value:

Bit Number Hex Meaning
00-030x0000-0x000FBoots Field Parameters:    
  • 0x0000 - Stays at the system bootstrap prompt.
  • 0x0001 - Boots the first system image in onboard Flash memory (EPROM).
  • 0x0002-0x000F- Specifies a default netboot filename. Enables boot system commands that override the default netboot filename.
060x0040
  • Ignore NVRAM contents
070x0080
  • Disable boot messages
080x0100
  • Break disabled
100x0400
  • IP broadcast with all zeros
5,11,120x0020, 0x0800, 0x1000
  • Console line speed
130x2000
  • Boots default ROM software if network boot fails
140x4000
  • IP broadcasts do not have net numbers
150x8000
  • Enables diagnostic messages
  • Ignores NVRAM contents
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confreg parameters

Benjamin Ninnemann wrote:

I referenced my confreg examples from

http://www.cisco.com/en/US/products/hw/routers/ps133/products_tech_note09186a008022493f.shtml

My question is, why is 0x2102 the default if you can easily use 0x3922 instead?

The benefit being that your console serial speed is 12 times faster.

Basically, it's backward compatible from the days when 9600 baud was about all you could push through a serial port for console access.

Yes, you *can* set it higher - but 9600 is a known default, and the first thing any experienced engineer will try if they need console access because they know it's likely to be right in 99.99% of cases.

As for the rest - well, Cisco may have some hidden stuff they don't want us outsiders to know - but who is to tell?

Cheers.

1 REPLY
Silver

confreg parameters

Benjamin Ninnemann wrote:

I referenced my confreg examples from

http://www.cisco.com/en/US/products/hw/routers/ps133/products_tech_note09186a008022493f.shtml

My question is, why is 0x2102 the default if you can easily use 0x3922 instead?

The benefit being that your console serial speed is 12 times faster.

Basically, it's backward compatible from the days when 9600 baud was about all you could push through a serial port for console access.

Yes, you *can* set it higher - but 9600 is a known default, and the first thing any experienced engineer will try if they need console access because they know it's likely to be right in 99.99% of cases.

As for the rest - well, Cisco may have some hidden stuff they don't want us outsiders to know - but who is to tell?

Cheers.

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