Cisco Catalyst 9404R Switch User Manual

step gets the BAUD and startup-config line console speed to match. A mismatch can cause loss of access
to the console port.
Any time you manually change the BAUD speed in the ROMMON (explicitly set a new speed), you may
lose console port access after a reload, or when switch boots, depending on what the BAUD speed and the
console port speed is in the startup-configuration. The console port speed must be changed to match the new
speed setting. After console access is restored, save the configuration to synchronize BAUD ROMMON
speed, startup-configuration, and line console speed. Enter the show bootvar command to verify the new
BAUD variable setting.
Note
Possible BAUD Mismatch—Scenario 1
Description—When you started off, the BAUD variable, start-up configuration and console port speed were
all set to 115200. After this, if you unset the BAUD parameter at some point…
1. This is an implicit change in the BAUD variable to 9600 and not an explicit setting in the ROMMON.
Further, the current console port session speed is still set to 115200 and you still have access.
2. Boot the image—Cisco IOS boots the image normally. The line console speed is initially retrieved from
BAUD (9600), but Cisco IOS parses the startup-configuration, and the speed is changed to 115200. This
matches the current console port speed.
3. Reload or power cycle the switch—Setup goes back to ROMMON mode and console access is lost because
the default BAUD speed of 9600 is effective and mismatched with the console port speed. Set console
port speed to 9600 to restore access.
4. Boot the image—Console port access is lost because the line console speed is initially retrieved from
BAUD (9600), Cisco IOS parses the startup-configuration, where the speed is set to 115200 and not in
sync with console port 9600 speed, and console port access is lost. Access is restored once console port
speed is set to 115200.
5. Reload or power cycle the switch—Setup goes back to ROMMON mode, but console access is lost again
due to mismatched BAUD of 9600.
In the above scenario, note the difference between an unset BAUD in step no.1 (where the implicit speed is
9600) and a set BAUD=9600 command (where the speed is explicitly set using the “set” command in
ROMMON). You are able to access the console until step no.4 because the BAUD has an unset, implicit speed
of 9600, but the speed was not actually changed from 115200. Once you reloaded or power cycled in step
no.5, the speed was set to 9600.
Solution 1—If you save running configuration to start-up configuration (copy system:running-config
nvram:startup-config) at step no. 2 then BAUD and the startup-configuration are synchronized with speeds
at 115200, and subsequent reloads will not interrupt access.
Solution 2—(Instead of performing the above steps) Configure the line console speed to 9600, change the
console port speed to 9600, and then save running configuration to start-up configuration, then BAUD in
ROMMON and startup-configuration will be synchronized with speeds at 9600.
Cisco Catalyst 9400 Series Switches Hardware Installation Guide
114
Troubleshooting
Cannot Connect to a Switch Through the Console Port

Cisco Catalyst 9404R Switch Specifications

General

Brand	Cisco
Model	Catalyst 9404R Switch
Category	Switch
Language	English