System Configuration Guide for Cisco Unified Communications Manager, Release 15 and SUs - Configure Enhanced Locations Call Admission Control

Publisher

Cisco Systems

URL

https://www.cisco.com/c/en/us/td/docs/voice_ip_comm/cucm/admin/15/systemConfig/cucm_b_system-configuration-guide-15/cucm_b_system-configuration-guide-14_chapter_01101.html

Published

2026-09-22

Updated

unknown

Accessed

2026-09-25

HTTP status

200

License

Cisco documentation; all rights reserved; no-redistribution; short excerpts and locators only

Source notes citing this source

• Link bandwidth allocations are set separately for three traffic types: audio, desktop video and immersive video. in context
• When Enhanced Locations CAC finds no bandwidth available for a call, Unified CM rejects the call and the caller hears a busy signal. in context
• Unless AAR is enabled and configured, an inter-location call that Enhanced Locations CAC denies simply ends in a busy signal; there is no automatic PSTN reroute. inferred in context
• Link weights set the relative priority of links, and Unified CM uses them to calculate the effective path between two locations as the path with the least cumulative weight. in context
• Enhanced Locations Call Admission Control in Unified CM Release 15 regulates audio quality and video availability over complex WAN topologies by modelling the network as locations (LANs) and the WAN links between them, each with bandwidth limits. in context
• The Release 15 guide warns that during network failures the bandwidth reservation path Unified CM calculates may not reflect actual network conditions. in context
• In an intercluster ELCAC design, the Hub_None location must be renamed in each cluster, otherwise it becomes a common location shared across clusters. in context
• The LBM Intercluster Replication Group is where the administrator chooses which local LBM servers act as hubs and which stay spokes, and lists bootstrap servers that replicate connectivity information to other hubs. in context
• The intra-location bandwidth for devices within a location defaults to Unlimited for all media types. in context
• By default the Cisco CallManager service talks to its local LBM service; an LBM group can instead point it at an active and a standby LBM for redundancy. in context
• LBMs given the hub role actively replicate location and link information between clusters; hubs discover each other through common connections and form a full-mesh replication network. in context
• The Cisco Location Bandwidth Manager feature service is off by default and must be activated in Cisco Unified Serviceability for Enhanced Locations CAC to work. in context
• The Location Bandwidth Manager must run on at least one node in the cluster, and Cisco recommends running it on each subscriber node that also runs the Cisco CallManager service. in context
• LBMs left in the spoke role take part in intercluster replication only indirectly, through the LBM hubs in their own cluster. in context
• A link is the connection between two locations, and each link is given bandwidth allocations and a weight. in context
• In Enhanced Locations CAC a location represents a LAN; it can contain endpoints or serve only as a transit location between links for WAN modelling. in context
• One supported way to manage an intercluster topology is to configure every location and link, with bandwidth allocations and weights, for the whole network in a single management cluster and let replication distribute it. in context
• Unified CM supports up to 2000 locations per cluster. in context
• The Release 15 guide states that bandwidth for media resources is not allocated through call admission control. in context
• Where bandwidth values assigned to a call conflict, the Release 15 guide says Unified CM uses the minimum of the assigned values. in context
• Cisco advises against changing LBM bandwidth settings during production hours because doing so can cause unnecessary CPU spikes. in context
• Regions set the bandwidth that the endpoints in a call between two regions may use, locations set the total bandwidth all calls between those locations may use, and each call's region bandwidth is deducted from the location's available bandwidth. in context
• With Enhanced Locations CAC, SIP intercluster trunks must be assigned to the Shadow location. in context
• For SIP trunks, the video classification (Desktop, Immersive or Mixed) is set with the Video Call Traffic Class field in the SIP Profile associated with the trunk. in context
• The Release 15 Enhanced Locations CAC task flow runs in this order: activate Location Bandwidth Manager, configure LBM group, configure locations and links, configure the LBM intercluster replication group, configure SIP intercluster trunks, then optionally configure CAC service parameters. in context
• TelePresence endpoints have a fixed video call classification of Immersive that cannot be changed. in context
• By default, the audio part of a video call is deducted from the video bandwidth pool, not from the audio pool. in context
• Enhanced Locations CAC controls audio quality and video availability across complex WAN topologies, including intercluster networks, by modelling locations and links with bandwidth limits. in context
• Enhanced Locations CAC needs the Cisco Location Bandwidth Manager feature service running on at least one cluster node, and that service is off by default. in context

Cite this source record

APA

WarmTransfer. (2026, September 22). System Configuration Guide for Cisco Unified Communications Manager, Release 15 and SUs - Configure Enhanced Locations Call Admission Control. WarmTransfer. https://warmtransfer.net/knowledge/sources/cisco-cucm-sysconfig-15-elcac

BibTeX

@misc{warmtransfer-cisco-cucm-sysconfig-15-elcac,
  title  = {System Configuration Guide for Cisco Unified Communications Manager, Release 15 and SUs - Configure Enhanced Locations Call Admission Control},
  author = {{WarmTransfer}},
  year   = {2026},
  url    = {https://warmtransfer.net/knowledge/sources/cisco-cucm-sysconfig-15-elcac},
  note   = {Cisco Systems, accessed 2026-09-25}
}