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The "Not Enough Bandwidth" error message appears on an IP phone when remote branch offices are called from the Central site

Core Issue

When the Cisco CallManager gateway location parameter is set to None, it is not assigned a location and there are no restrictions on bandwidth usage or consumption. A large number of calls through the gateway and back to the Cisco CallManager central site can potentially exhaust the available bandwidth between the sites, which causes the Not Enough Bandwidth error message to appear.

Resolution

In order to resolve this issue, use the low bandwidth codec between the sites. In order to do this, configure locations and regions for both IP phones and their site gateway. Configured locations (bandwidth) or regions (codecs) for IP phones cannot be guaranteed to serve their purpose unless gateways are also assigned to locations.

Refer to the Locations and Regions section of Configuring Locations for more information.

This issue is important to connections that use compression in order to preserve bandwidth in lower bit rate codecs, such as G.729 and G.723. IP phones and gateways must also be assigned a region.

This issue can be more common for initial configurations or networks that have increased the site-to-site bandwidth usage.

In installations where the locations and regions are already in place, this error can appear for these reasons:

  • The number of allowed calls between sites is exceeded. In other words, all the allowed bandwidth is consumed. Each time a call is initiated between locations, Cisco CallManager deallocates a certain amount of bandwidth from the configured pool based upon the codec used for the call. When there is not enough bandwidth in the pool for a given call, the Not Enough bandwidth message appears on the phone that tries to make the call.

  • In some of the initial versions of Cisco CallManager, this error sometimes occurs even when the limit is not reached. This is due to bugs in Cisco CallManager where the bandwidth is not returned to the pool by the disconnected calls. These problems are fixed in the latest service packs. In order to resolve the issue, upgrade to the latest service packs.

  • Also, if possible try to restart the Database Layer (DBL) Monitor Service.

Restart Cisco CallManager for an immediate workaround to this problem.

In order to monitor bandwidth, complete these steps:

  1. Create a LocationsTraceDetailsFlag service parameter in Cisco CallManager service parameters. Make the type boolean, and set the value to True.

  2. Enable detailed traces for the Cisco CallManager service. Specify the calling and called number, as well as when the problem occurs.

  3. Check the amount of bandwidth available in all locations with Perfmon. Add the counters CurrentAvailableBandwidth and MaxAvailableBandwidth from the Cisco Locations object. This puts bandwidth values in the trace file for each call. Look at the trace file in order to determine if it runs out of bandwidth and when.

Refer to Cisco bug ID CSCdu78298 Music on Hold (MoH) ignores Locations Connection Admission Control (CAC) leading to voice quality degradation for more information.

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