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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
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Known Affected Releases

15.0(1)M3 15.3(3)M 15.4(0.4)T

Description (partial)

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

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.

Related Community Discussions

Metro boot DHCP
Hi, I'm currently testing a Metro ME3400G-2CS-A, before we purchase new ones. It's completely up-to-date, but when I try to boot with config download from TFTP "boot host dhcp", the device crashes with warning: *Mar  1 00:01:32.517: %SYS-6-STACKLOW: Stack for process Boot HostDHCP running low, 0/6000 The config that he try's to download is only 57 line big and 1147 characters -_-'. Anyone any idea how to fix this? Kind regards, Ricardo Brock
Latest activity: Aug 11, 2016
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