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Cisco Bug: CSCtb17730 - Modular VSS - Crash or High CPU after fast-hello removed

Last Modified

Feb 20, 2018

Products (6)

  • Cisco IOS
  • Cisco Catalyst 6500 Series Virtual Switching Supervisor Engine 720 with 10GE uplinks
  • Cisco ME 6524-GS Ethernet Switch
  • Cisco Catalyst 6500 Series Supervisor Engine 32 / MSFC2A
  • Cisco ME 6524-GT Ethernet Switch
  • Cisco Catalyst 6500 Series Supervisor Engine 720 / MSFC3

Known Affected Releases

12.2(32.8.11)XJC273.9 12.2(33)SXI2a

Description (partial)

On a VSS system running modular IOS, the active and standby switch processors may see one of the following:
-Extremely high CPU in ios-base
- "show proc detailed ios-base" would show thread in Ready state which is showing high CPU utilization.

This state is entered at some time after VSS dual-active fast-hello is un-configured.  It can be triggered by either removing fast-hellos from the interface or globally disableing fast hellos under the virtual domain.

Remove from interface:
(config-if)#no dual-active fast-hello

Globally disable:
 (config)# switch virtual domain <#>
 (config-vs-domain)#no dual-active detection fast-hello
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