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Cisco Bug: CSCsz30049 - memory corruption by queuing on mix of MLP and PPP on same physical int

Last Modified

Jan 23, 2017

Products (1)

  • Cisco IOS

Known Affected Releases

12.2(31)SB14 12.2(33)SRC5 12.4(200.10) 12.4(24)T7

Description (partial)

Symptoms: A router may crash with memory corruption or with one of the two
 following messages:
  %SYS-6-STACKLOW: Stack for process HQF Shaper Background running low, 0/6000
  %SYS-6-STACKLOW: Stack for process PPP Events running low, 0/12000
 In the case of memory corruption, a corrupted block will be in an address range
 very close to process or interrupt level 1 stack (this information is available
 in the crashinfo file).
 Conditions: The symptom is observed on routers running Cisco IOS Release 12.2SB
 when ALL of the following conditions are met:
 1. The router is configured for VPDN/L2TP.
 2. There is a mixture of PPPoVPDN and "MLP Bundle" users.
 3. QoS service policy with queuing actions (bandwidth guarantee or shaper) is
 applied to virtual access interfaces for both types of users.
 Here is a way to find out if there is normal PPP users or MLP users:
 PPP User via CLI:
 Router#sh user | inc PPP.*00 [1-9]
   Vi4          user#wl-cp03-7k2#4 PPPoVPDN     00:00:00
 MLP via CLI:
 Router#sh user | inc MLP.*00 [1-9]
   Vi8          user#wl-cp04-7k2#5 MLP Bundle   00:00:00
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