Cisco Bug: CSCul05056 - SYS-6-STACKLOW due to NBAR config
Last Modified
May 28, 2020
Products (74)
- Cisco IOS
- Cisco 1905 Serial Integrated Services Router
- Cisco 819 Hardened Integrated Services Router
- Cisco C897VA Integrated Services Router
- Cisco 886VAG 3G Integrated Services Router
- Cisco VG204XM Analog Voice Gateway
- Cisco 2951 Integrated Services Router
- Cisco 861W Integrated Services Router
- Cisco C892FSP Integrated Services Router
- Cisco 892W Integrated Services Router

Known Affected Releases
15.0(1)M3 15.3(3)M 15.4(0.4)T
Description (partial)
Symptom: A Cisco router may crash when configuring NBAR or any other feature which enables NBAR internally. In the crash log file, the crash will be shown as a STACKLOW condition. Examples of this are: %SYS-6-STACKLOW: Stack for process Config Probe running low, 0/12000 %SYS-6-STACKLOW: Stack for process SSH Process running low, 0/12000 %SYS-6-STACKLOW: Stack for process InitializeNbarAPI running low, 0/12000 Conditions: This crash is triggered by enabling NBAR directly or indirectly through another feature. Two such examples are configuring NAT on an interface or configuring NBAR on an interface. For example: (config)#interface gigabitethernet0/1 (config-if)#ip nbar protocol-discovery (config)#interface gigabitethernet0/1 (config-if)#ip nat inside The router may not crash depending on how the configuration is done. For example configuring the feature over the console will not cause a crash. Configuring the feature over SSH, through FTP, Smart Install, etc though will cause the crash.
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