This document provides information on how to troubleshoot when the
Cisco CallManager Conference Bridge fails with the
KEEPALIVE_FAILED error message. The conference
bridge becomes unavailable for a potentially indefinite period of time until it
There are no specific requirements for this document.
The information in this document is based on the Cisco CallManager
4.1(3) and Cisco 2800 Series Router that runs Cisco IOS® Software Release
The information in this document was created from the devices in a
specific lab environment. All of the devices used in this document started with
a cleared (default) configuration. If your network is live, make sure that you
understand the potential impact of any command.
Technical Tips Conventions for more information on document
Hardware-enabled conferencing provides the ability to support voice
conferences in hardware. Digital Signaling Processors (DSPs) convert multiple
Voice over IP Media Streams into TDM streams that are mixed into a single
conference call stream. The number of conferences supported depends on the
number of DSPs available. So, if the conference bridges are not terminated
properly, the DSPs cannot be reused. For more details about how to configure a
conference bridge on an IOS gateway, refer to
and IOS Gateway DSP Farm Configuration Example.
If a Cisco CallManager becomes unreachable to the conference bridge it
was registered to while a conference was active, the conference bridge ends up
in the KEEPALIVE_FAILED state. The conference
bridge also continues to send media signals, potentially over the WAN for a
long time after all parties have left the conference and the DSP resources are
not able to be reused for more conferences.
The KEEPALIVE_FAILED error is found
because the conference bridge does not switch back to another CallManager that
is available in the cluster. In order to solve this problem, you need to
mention the switchover method to use in the gateway.
When the communication link between the active Cisco Unified
CallManager and the Skinny Call Control Protocol (SCCP) client goes down, the
SCCP client tries to connect to one of the secondary Cisco Unified CallManagers
with the use of one of these switchover methods:
Graceful—The Cisco Unified CallManager switchover
happens only after all the active sessions are terminated gracefully. This is
the default method.
Immediate—Regardless of whether there is an active
connection or not, the SCCP client switches over to one of the secondary Cisco
Unified CallManagers immediately. If the SCCP Client is not able to connect to
a secondary Cisco Unified CallManager, it continues to poll for a Cisco Unified
The switchover method can be mentioned under the sccp ccm
gateway(config)#sccp ccm group 1
gateway(config-sccp-ccm)#switchover method immediate
Note: If you have multiple profiles configured for conferencing in the
dspfarm, use the switchover method as graceful.
In order to terminate the conference bridges that send media
messages, the RTP message should timeout. This can be done when you change the
receive RTP timer in the gateway configuration.
gateway(config-gateway)#timer receive-rtp 180
The default timeout happens only after 1200 secs (20