Showing results for 
Search instead for 
Did you mean: 
Roger Nobel
Cisco Employee
Cisco Employee


802.1x using MAB is working until you reboot the switch. After shut/no shut or re-auth is required to get MAB working.

Cause / Problem Description

Race condition for radius server communication task and eap task (MAB).

Conditions / Environment

802.1x using MAB


Seems to be common known issue (race condition).
There is a bug id CSCtj46641 which is J-Status pointing to CSCsu90538 .



Suggest some test to customer and potential workaround to test.

1. Either adjust the config from a networking perspective (e.g. no spanning-tree) to ensure the RADIUS connection is up asap.

If we configure: 'no spanning-tree vlan x' then this issue should no longer seen.


This maybe still not working as we still relay on short time.


2. Adjust the mab config so that it either re-tries to authenticate periodically or else re-initialises when the server comes back.

The former can be done with the following config:

authentication timer restart 60
authentication event server dead action authorize vlan 11
authentication event server alive action reinitialize


This is not a good choice since we would have very short authentication periode in a life system



3. Create system-startup kron job which is run once at system startup.


This is not possible since running again and again

Create a policy-list which clears all authentication sessions (manual re-auth)

kron occurrence autostart in 2 recurring system-startup
policy-list force-reauth
kron policy-list force-reauth
cli clear authentication session

This will clear all sessions every 2 minutes after the system is up and again and again.

Not what we like to have. Option 3 is not an option.



4. This is the configuration solution work around

event manager applet onboot

event timer cron cron-entry "@reboot"

action 1.10 wait 20

action 2.10 cli command "enable"

action 2.20 cli command “clear authentication session "

action 6.10 syslog msg "cleared auth sessions"

This is the solution!


Getting Started

Find answers to your questions by entering keywords or phrases in the Search bar above. New here? Use these resources to familiarize yourself with the community:

Recognize Your Peers
Quick Links