Support for Resource Availability Indication Over SIP Trunks
The Support for Monitoring Utilization of Critical Resources on Gateway Router, Cisco UBE and Cisco UCME and Reporting Over SIP Trunks feature implements monitoring of resource utilization and reporting functionality over the Session Initiation Protocol (SIP) trunk on the Cisco IOS gateway, Cisco Unified Border Element (Cisco UBE) and Cisco Unified Communications Manager Express (Cisco UCME). This feature supports monitoring of CPU, memory, Digital Signaling Processor (DSP) and the DS0 port on the Cisco IOS gateway and reporting the status to external devices using SIP OPTION mechanism.
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Restrictions for the Support for Resource Availability Indication Over SIP Trunks Feature
The number of resource monitoring entities should be limited to a maximum of five.
The target device configured on the Cisco IOS gateway and the OPTIONS message obtained from the external polling device must be the same to accept the resource status query. For example, if an IP address is configured as the target on the Cisco IOS gateway, it is expected that the OPTIONS message coming into the Cisco IOS gateway will have the same IP address. The same applies if a Fully Qualified Domain Name (FQDN) is configured against the target device.
Information About the Support for Resource Availability Indication Over SIP Trunks Feature
Overview of the Support for Resource Availablity Indication Over SIP Trunks
The Support for Resource Available Indication Over SIP Trunks feature enables monitoring of CPU, memory, DSP, and DS0 resources on the Cisco IOS gateway and reporting of the status to external device using the gateway resources. The reporting from the gateway takes place either based on a configured time interval or on the configured threshold crossover. The gateway also supports extracting the gateway resource information from the external entity either on periodic or nonperiodic basis.
The monitoring and reporting of resources is achieved by SIP OPTIONS using x-cisco-rai headers. The highlights of monitoring and reporting of resources are as follows:
Resource groups are created by grouping the required resource monitoring entities together and providing each of the resource groups a unique index value.
The required monitoring and reporting parameters are applied on the resource groups for monitoring the selected resource entities.
In the periodic reporting, Resource Allocation Indication (RAI) information is reported based on a periodic-interval value configured through a CLI. The periodic reporting is disabled by default.
In the threshold-based reporting, RAI information is reported when one of the resources reaches an out-of-resource state. Threshold-based reporting is disabled by default.
Call treatment is not handled as part of this feature on the gateway. If call treatment needs to be performed along with reporting, then the call threshold feature needs to be configured appropriately with desired threshold values. The gateway supports CPU, memory, and maximum number of calls per interface.
Benefits of the Support for Resource Availablity Indication Over SIP Trunks
Intelligent routing can be performed by Customer Voice Portal (CVP) if the Cisco IOS gateway passes information with the methodology provided by this feature.
Call handling is performed more efficiently in Voice over Internet Protocol (VOIP) networks where CVP uses the Cisco IOS gateway for both VoiceXML (VXML) application as well as time-division multiplexing (TDM) calls for Public Switched Telephone Network (PSTN) connectivity.
By monitoring and reporting the usage status of the gateway resources and generic resources to the external entity, you can take decisions based on the current load and status of various gateway resources.
Migration from H.323 to SIP is made easier.
Overview on Monitoring and Reporting of Gateway Resources
The gateway uses the x-cisco-rai header in the OPTIONS message to report the resource utilization to the routing or monitoring entities.
The Augmented Backus-Naur Form (ABNF) format of reporting is used to report the status of the report utilization to the monitoring entity. The Cisco IOS gateway may not use all the fields. Provision is also made for adding new resource types and new parameters for the resources.
The following is the format of the header used for reporting:
The rules for constructing the header are as follows:
SYSTEM is a mandatory parameter that should be the first resource for a given device. Other resource-name-param values are optional parameters.
The resource-identity-param parameter is a mandatory parameter within the SYSTEM resource-name-param parameter.
At least one resource parameter (resource-params) should be present. If the resource-available-param parameter is present, the resource-total-param parameter should also be present so that the resource-used-param parameter can be calculated.
For the SYSTEM resource-name-param parameter, the provision of a resource-status-param parameter is mandatory.
Following are the examples of the reporting format in the SIP OPTIONS message:
Example 1: Cisco IOS Gateway Sending Resource Header when the Resources are Available
Gateway Triggered Reporting to Routing Monitoring Entity
In gateway triggered reporting, the gateway sends the resource utilization information in an OPTION message to the external entity. The gateway includes a supported header with the option tag x-cisco-rai to indicate that this OPTION message carries the resource availability information. The trigger to send the OPTION message can be either periodic, or threshold based, or both.
In the periodic reporting mode, reporting is triggered based on a preconfigured timer value. This type of reporting is used to collect information on a resource usage.
Threshold Triggered Reporting
In the threshold triggered reporting mode, reporting is triggered depending on the threshold levels configured for the resources that are being monitored. This mode of reporting is used to inform the external entity of the availability or nonavailability of the gateway to service further call requests from the external entity. Threshold triggered reporting is disabled by default.
Routing Monitoring Entity Triggered Reporting
In routing or monitor triggered reporting, the external entity can extract the resource information from the gateway using the SIP OPTIONS message. The gateway expects the x-cisco-rai tag in either the require: or supported: header fields for an incoming OPTIONS message. The presence of the x-cisco-rai tag in any one of the header fields informs the gateway that this option is to retrieve the gateway resource information.
Reporting Mechanism over SIP Trunk
The monitoring and reporting of gateway resources to an external entity is achieved by SIP OPTIONS using x-cisco-rai headers. The sample OPTIONS message format is as provided below.
Example Configuring Resource Groups and Resource Monitoring Parameters
The following example shows how to configure the resource group 1 to monitor CPU, DS0, DSP, and memory resources:
voice class resource-group 1
resource cpu 1-min-avg threshold high 50 low 30
resource ds0 threshold high 50 low 30
resource dsp threshold high 50 low 30
resource memory total-mem threshold high 50 low 30
periodic-report interval 30
Example Configuring SIP RAI Mechanism
rai target ipv4:220.127.116.11 resource-group 1 transport udp
rai target dns:whitesmoke resource-group 2 transport tcp
rai target ipv6:[2217:10:10:10:10:10:10:2] resource-group 3 transport tcp
rai target dns:butterfly resource-group 4 transport tcp tls scheme sips
rai target ipv4:10.13.40.84 resource-group 5 transport tcp
rai target ipv4:10.13.40.83 resource-group 1
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Feature Information for the Support for Resource Availability Indication Over SIP Trunks
The following table
provides release information about the feature or features described in this
module. This table lists only the software release that introduced support for
a given feature in a given software release train. Unless noted otherwise,
subsequent releases of that software release train also support that feature.
Use Cisco Feature Navigator to find information about platform
support and Cisco software image support. To access Cisco Feature Navigator, go
An account on Cisco.com is not required.
Table 1 Feature Information for the Support for Resource Availablity Indication Over SIP Trunks Feature
Support for Monitoring Utilization of Critical Resources on Gateway Router, Cisco UBE and Cisco UCME and Reporting Over SIP Trunks
The Support for Monitoring Utilization of Critical Resources on Gateway Router, Cisco UBE and Cisco UCME and Reporting Over SIP Trunks feature implements monitoring of resource utilization and reporting functionality over SIP trunk on Cisco IOS gateway, Cisco UBE and Cisco UCME.
The following commands were introduced or modified: