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Cisco Bug: CSCuc08324 - PPTP or L2TP tunnel can stop working suddenly if MPPE is negotiated

Last Modified

Jul 12, 2021

Products (2)

  • Cisco Catalyst 4000 Software
  • Cisco 2600 Series Multiservice Platforms

Known Affected Releases

15.0(1)M4 15.1(4)M4 15.4(2)T1

Description (partial)

PPTP or L2TP tunnel may suddenly stop passing traffic if MPPE is negotiated. The following error counter is incremented:

show int virtual-access3
     91 unknown protocol drops

The following command should present in configuration for MPPE to be negotiated:

interface Virtual-Template4
 ppp encrypt mppe auto
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