Cisco Cisco ASR 5700
Mobility Management Entity Overview
▀ Features and Functionality - Base Software
▄ MME Administration Guide, StarOS Release 18
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Congestion control monitors the system for conditions that could potentially degrade performance when the system is
under heavy load. Typically, these conditions are temporary (for example, high CPU or memory utilization) and are
quickly resolved. However, continuous or large numbers of these conditions within a specific time interval may have an
impact the system’s ability to service subscriber sessions. Congestion control helps identify such conditions and invokes
policies for addressing the situation.
under heavy load. Typically, these conditions are temporary (for example, high CPU or memory utilization) and are
quickly resolved. However, continuous or large numbers of these conditions within a specific time interval may have an
impact the system’s ability to service subscriber sessions. Congestion control helps identify such conditions and invokes
policies for addressing the situation.
Congestion control operation is based on configuring the following:
Congestion Condition Thresholds: Thresholds dictate the conditions for which congestion control is enabled
and establishes limits for defining the state of the system (congested or clear). These thresholds function in a
way similar to operation thresholds that are configured for the system as described in the Thresholding
Configuration Guide. The primary difference is that when congestion thresholds are reached, a service
congestion policy and an SNMP trap, starCongestion, are generated.
way similar to operation thresholds that are configured for the system as described in the Thresholding
Configuration Guide. The primary difference is that when congestion thresholds are reached, a service
congestion policy and an SNMP trap, starCongestion, are generated.
A threshold tolerance dictates the percentage under the configured threshold that must be reached in order for
the condition to be cleared. An SNMP trap, starCongestionClear, is then triggered.
the condition to be cleared. An SNMP trap, starCongestionClear, is then triggered.
The following system resources can be monitored:
System CPU usage
System service CPU usage (Demux-Card CPU usage)
System Memory usage
License usage
Maximum Session per service
Service Congestion Policies: Congestion policies are configurable for each service. These policies dictate how
services respond when the system detects that a congestion condition threshold has been crossed.
Congestion control can be used in conjunction with the load balancing feature provided on the MME. For more
information on MME load balancing, refer to the
information on MME load balancing, refer to the
For more information or to configure Overload Control using the basic Congestion Control functionality, refer to the
Congestion Control chapter in the Cisco ASR 5x00 Series System Administration Guide.
Congestion Control chapter in the Cisco ASR 5x00 Series System Administration Guide.
For more information about the Enhanced Congestion Control functionality (a licensed feature), refer to the Enhanced
Congestion Control and Overload Control chapter in this guide.
Congestion Control and Overload Control chapter in this guide.
Define Same TAI in Multiple TAI Lists
Prior to 17.0, the MME could have a tracking area in only one tracking area list (TAI List). Consequently, the tracking
area list assigned to subscribers attaching from different TAIs will be same, even if the adjacency of these tracking areas
is not same. This results in MME getting TAUs even as subscribers moved to the adjacent area.
area list assigned to subscribers attaching from different TAIs will be same, even if the adjacency of these tracking areas
is not same. This results in MME getting TAUs even as subscribers moved to the adjacent area.
With this enhancement, the MME will allow operators to configure adjacency lists as TAI Lists, thus reducing the
Tracking Area Updates (TAU) received by MME. This feature enables the MME to send configured customized TAI
List in ATTACH_ACCEPT/TAU_ACCEPT when a request is received from the custom or border TAIs.
Tracking Area Updates (TAU) received by MME. This feature enables the MME to send configured customized TAI
List in ATTACH_ACCEPT/TAU_ACCEPT when a request is received from the custom or border TAIs.
The reduced TAU results in less signaling load on the MME and better operational efficiency.
Emergency Call Release
Notifying the GMLC of the emergency call release event allows the GMLC to delete all information previously stored
for the emergency call in accordance with regulations.
for the emergency call in accordance with regulations.