Technical information

Troubleshooting Cisco 3900 Series, 2900 Series, and 1900 Series ISRs

Jumper Settings

Cisco 2900 and 3900 Series Hardware Installation

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Check the router chassis or software.

• Router boots, but the console screen is frozen.

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Check the external console connection.

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Verify that the parameters for your terminal are set as follows:

(a) The same data rate as configured for the router (9600 baud is the default)

(b) 8 data bits

(d) No parity generated or checked

• Router powers on and boots only when a particular card is removed.

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Check the card. Refer to “Obtaining Documentation and Submitting a Service Request” for

warranty and customer service contact information.

• Router powers on and boots only when a particular cable is disconnected.

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There may be a problem with the card or cable. Refer to “Obtaining Documentation and

Submitting a Service Request” for warranty and customer service contact information.

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Check that only one console cable is connected. Either a USB console or RJ-45, but not both.

Jumper Settings

If a ROM monitor failure occurs, you may need to change a jumper setting on the motherboard so the

router can boot for troubleshooting. Procedures for accessing the motherboard are described in

“Removing and Replacing the Services Performance Engine” (Cisco 2900 and 3900 Series Routers).

You may need to set one of the following jumpers on Cisco 3900 and Cisco 2900 ISRs, or operate the

Baud Reset Button on Cisco models 1905/1921:

• DUART DFLT—Sets the console connection data rate to 9600 regardless of user configuration

Change this setting if the console displays garbage characters. The jumper forces the data rate to a

known good value.

• BOOT DFLT—Boots from the read-only boot image in case an upgrade is corrupted

Change this setting if the router consistently hangs or crashes after a ROM monitor upgrade.

If you change either of the first two settings as shown, the router stays in the new configuration during

subsequent power cycles and the jumper can be removed.

Note The jumpers are not needed to troubleshoot Cisco IOS problems. If the Cisco IOS software becomes

corrupted, remove the CompactFlash memory card to force the router to boot in ROM monitor mode.

Change these settings only after consulting with your service representative or Cisco technical support.

Wireless Reception

Wireless communication is dependent upon the propagation of radio waves. Many environmental factors

influence radio waves. The Cisco Multiband Swivel-Mount Dipole Antenna document Installation Notes

section describes factors affecting this.