Configuration register is set to break enabled, resulting in the Multilayer Switch Feature Card (MSFC) going to ROMmon any time a break is issued.
Plugging a terminal into the console port periodically produces a ROMmon prompt. A misbehaving or reloading terminal may accidentally send the router a signal similar to the break sequence. If the MSFC configuration register is set to "break enable" this will put the MSFC in ROMmon mode.
To disable the break key, reset the router from ROMmon mode to boot the router to normal router mode.
Issue a show version command and check the configuration register setting on the last line of the output. If the configuration register is set to one of the following, the break key is enabled:
Configuration register is 0x2 or Configuration register is 0x2002
Setting the configuration regitster to 0x2102 disables the break key. To change config register to 0x2102, issue the following command:
C6006-Y> (enable) switch console Trying Router-15... Connected to Router-15. Type ^C^C^C to switch back... Router#config t Enter configuration commands, one per line. End with CNTL/Z. Router(config)#config-reg 0x2102 Router(config)#^Z Router#wr mem
The new configuration register setting will not take affect until the switch has been reloaded. Configuration register is 0x2 (will be 0x2102 at next reload).