Preview Tool

Cisco Bug: CSCtd42708 - high CPU in SIP pointing to 491/ack loop

Last Modified

Jul 07, 2017

Products (1)

  • Cisco Unified Communications Manager (CallManager)

Known Affected Releases


Description (partial)


Cisco IOS VoIP gateway configured for IPIPGW/CUBE may experience issues of high CPU utilization.


Under rare conditions the Cisco IOS gateway may get into a state where the processes associated with SIP (as seen in <CmdBold>show process cpu<noCmdBold>) may get into a state where they are running extremely high causing further calls through the router to fail.

This is due to the gateway and 3rd party device in a SIP '491 Requent Pending' and ACK loop.  THis has been shown to occur in environments with large number of SIP REFER transfers.

This can be seen in <CmdBold>show sip statistics<CmdBold> and look for the RequestPending value showing an high and increasing output count.
Bug details contain sensitive information and therefore require a account to be viewed.

Bug Details Include

  • Full Description (including symptoms, conditions and workarounds)
  • Status
  • Severity
  • Known Fixed Releases
  • Related Community Discussions
  • Number of Related Support Cases
Bug information is viewable for customers and partners who have a service contract. Registered users can view up to 200 bugs per month without a service contract.