HP J3138A, Installation Manual

Page: 58 / 104

4-8
Maintaining the HP AdvanceStack Internet Router
Virtual Configuration Register Settings
M
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Virtual Configuration Register Settings
The router has a 16-bit virtual configuration register, which is written into
NVRAM. You might want to change the virtual configuration register settings
for the following reasons:
■
Set and display the configuration register value
■
Force the system into the ROM monitor or boot ROM
■
Select a boot source and default boot filename
■
Enable or disable the Break function
■
Control broadcast addresses
■
Set the console terminal baud rate
■
Recover a lost password (ignore the configuration file in NVRAM)
■
Enable TFTP server boot
Table 4-3 lists the meaning of each of the virtual configuration memory bits,
and defines the boot field names.
C A U T I O N
To avoid confusion and possibly halting the router, remember that valid
configuration register settings might be combinations of settings and not just
the individual settings listed in table 4-3. For example, the factory default value
of 0x2102 is a combination of settings.
Table 4-3. Virtual Configuration Register Bit Meanings
a. The factory default value for the configuration register is 0x2102. This value is a combination
of the following: bit 13 = 0x2000, bit 8 = 0x0100, and bits 00 to 03 = 0x0002.
Bit No.
a
Hexadecimal Meaning
00–03 0x0000–0x000F Boot field
06 0x0040 Causes system software to ignore the contents of
NVRAM (startup-config)
07 0x0080 OEM bit is enabled
08 0x0100 Break is disabled
10 0x0400 IP broadcast with all zeros
11–12 0x0800–0x1000 Console line speed
13 0x2000 Load the boot ROM software if a Flash boot fails five
times
14 0x4000 IP broadcasts do not have network numbers
15 0x8000 Enable diagnostic messages and ignore the contents
of NVRAM