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New Member

Cisco 837 ADSL Router boots into Rommon when a modem is attached


I am using a 837 adsl router at a remote office with a gre tunnel back to our main office, I have a Zoom 56k modem attached to the console port for dial backup incase the adsl goes down. Every thing seems to be working fine except for the fact that if the router is rebooted with the modem attached it boots into Rommon. If you turn the modem off and then reboot the router it is fine, I have also tried a us robotics modem and get the same results.

Any sugestions would be apreciated


Forest Penland

Sierra Pacific Industries

New Member

Re: Cisco 837 ADSL Router boots into Rommon when a modem is atta

The ROM monitor code executes upon power-up, reset, or when a fatal exception occurs. ROM monitor depending the boot values used will use the boot sequence based on a criteria:

The following functionality is built into the ROM monitor:

[1]Power-on confidence test

[2]Hardware initialization

[3]Boot capability (allows manual boot and autoboot)

[4]Debug utility and crash analysis

[5]Monitor call interface (EMT calls—the ROM monitor provides information and some functionality to the running system images via EMT calls)

[6]File system (the ROM monitor knows the simple file system and supports the newly developed file system through the dynamic linked file system library [MONLIB])

[7]Exception handling

Depending on how the configuration register is set, an exception will cause your router to boot into ROM-monitor mode.

Another way that you enter ROM-monitor mode is sending ctrl-break, or ctrl-c...I bet the modem is sending a disconnect and ROM-monitor is inturpreting this as a control-break?

New Member

Re: Cisco 837 ADSL Router boots into Rommon when a modem is atta

Thanks for the info,

Thats what I figured, that the modem is sending somthing that the router is inturpreting as a control-break. Has anyone else had this problem? Or any ideas on a solution?


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