SIP Signaling - Overload Control

The SIP Overload Control object configures the IMG 2020 to be able to control SIP signaling traffic between two SIP networks. The SIP Overload Control object can be configured to accomplish the following.

1. Transmit or Inform the entity in a network that the IMG 2020 has reset or failed and has come back into service. At this point, calls can now resume.

2. Block or Unblock calls coming from a network.

3.  Monitor resource usage and inform entities in a network and restrict calls when a maximum number is reached.

4. Monitor and inform entities in a network and resume calls when the resources available go below a set threshold after reaching a set maximum.

Refer to the topics in the Related Topics section below for more information.

Web GUI Page

Dialogic > Routing Configuration > Channel Groups > Channel Group (SIP) > IP Network Element > Node Association > New Overload Control

Open

Maximum Objects

One SIP Overload per Channel Group

Related Topics and Dependencies

No dependencies. Refer to SIP Overload Control Overview topic for more information.

Field Descriptions

The fields below configure individual functionality that utilize the SIP OPTIONS message.

Node Reset Notification

Disabled (Default)

Receive SIP OPTIONS (node reset) message: If the remote external SIP gateway resets and the SIP Options is configured on it, it will send the SIP Options (node reset) message to the IMG 2020. When the IMG 2020 receives the SIP OPTIONS (node reset) message, it will respond with a 503 Service Unavailable message.

Transmit SIP OPTIONS (node reset) message: If the IMG 2020 resets, the SIP Options message will not be generated nor will it be transmitted. The SIP Options functionality is disabled.

Enabled

Receive SIP OPTIONS (node reset) message: If the remote external SIP gateway resets and the SIP Options is configured on it,  it will send the SIP Options (node reset) message to the IMG 2020. When the IMG 2020 receives the SIP OPTIONS (node reset) message, it will release any calls that are connected between the IMG 2020 and the external gateway that sent the SIP Options message. The IMG 2020 will also release any calls by transmitting the BYE message on the outgoing channel group of the calls. Once resources have been released, the IMG 2020 will transmit the SIP OPTIONS (call accept) message informing the remote node it is ready to accept calls.

Transmit SIP OPTIONS (node reset) message: The IMG 2020 resets. Once the node comes back into service, it will transmit to the remote gateway the SIP OPTIONS (node reset) message informing the external gateway that it had reset and it is back in service and can start accepting calls again.

Refer to the SIP Overload Control Overview topic for more information on the Node Reset Notification field.

Block Incoming Calls

Through use of the SIP OPTIONS message, a user can manually block and unblock incoming calls from an external gateway

Unblocked- When the IMG 2020 is configured as Unblocked, if a call is received, the IMG 2020 accept the call and pass it to the outgoing side.

Blocked- When the IMG 2020 is configured as blocked, if a call is received the IMG 2020 will respond with a 503 Service Unavailable message.

Refer to the SIP Overload Control Overview topic for more information on the Block Incoming Calls field.

Congestion Monitoring

The IMG 2020 can monitor the CPU Usage, SIP message handles usage, and the IP Channels usage. If one or more of the usage thresholds configured in the system are exceeded, the IMG 2020 will inform the external SIP entities through the SIP OPTIONS message that congestion has occurred. The IMG 2020 can also inform the SIP entities when the usage thresholds have returned back past a specified level.

Disabled (Default)- The IMG 2020 does not monitor nor will it stop incoming calls if the system goes into congestion.

Enabled- The IMG 2020 will monitor incoming calls. If one or more usage parameters exceed their pre-configured values, the IMG 2020 will inform the external SIP entity that congestion is occurring. Once the usage parameters fall below a second pre-configured value, the 2020 will again inform the external SIP entity that congestion levels are back to normal. This information is sent through the SIP OPTIONS message.

Refer to the SIP Overload Control Overview topic for more information on the Congestion Monitoring field.