SIP VFU

When a Codec sends out a video frame, it initially will transmit frames described as I frames (reference frames). The I Frame contains the complete information needed to display a picture. To save on bandwidth, instead of continuously transmitting the I frames, a technique is used where the subsequent video packets sent after the I Frame are just updates to the initial picture. These updates which are labeled P Frames are sent to minimize the amount of video data that needs to be transmitted from one video system to another. Occasionally the P Frames become corrupted through different issues such as packet loss, jitter, or there is too much information. At this point the far end would request a Video Fast Update request. The VFU requests a new I Frame be sent with the full reference frame of video information. Once the new I-Frame is sent, the subsequent packets sent will be P-Frames starting with the new I Frame just sent. The VFU feature is always running on the IMG 2020 and cannot be disabled.

VFU Delayed handling is a functionality that allows the IMG 2020 to handle ill-behaved applications that may flood the IMG 2020 with VFU requests. The IMG 2020 would in turn flood the remote video transmitter by interworking and sending it these requests. The remote video receiver would also get flooded with I-Frame requests from the IMG 2020. The SIP VFU object is used to handle this type of issue. The IMG 2020 can configure in a time delay where the IMG 2020 will not handle any additional VFU requests until after the delay expires. Refer to information below.

Web GUI Page

Dialogic > Profiles > SIP Profiles > SIP Profile > New SIP VFU (Video Fast Update)

Maximum Objects

One VFU (Video Fast Update) object per SIP Profile object.

Field Descriptions

VFU Delay (Default= 0 seconds)

VFU Delay handling gives the IMG 2020 the ability to handle applications that could flood it with VFU requests. If an application floods the IMG 2020 with too many VFU requests, the IMG 2020 will need to "overwork" to process all the rogue requests. To handle this, the VFU Delay field can be configured so that if the IMG 2020 gets flooded with VFU requests, the IMG 2020 will pass only the first request and no other VFU requests are interworked until after the delay timer has expired. In the VFU Delay field, select from drop down menu the number of seconds to wait before interworking any subsequent VFU requests. Values range from 0 to 10 seconds.

VFU Interval (Default = 100 seconds)

The VFU Interval field and the VFU Limit field work with each other to monitor the number of received VFU requests received. The Video Fast Update feature can monitor the number of VFU requests that are received in a specific interval of time. If more than the pre-configured number of requests configured in the VFU Limit field below is exceeded during the Time Interval configured in the VFU Interval field the IMG 2020 will generate an event log indicating the number of VFU Requests limit, the time of the event, and the information needed to identify the remote device sending the VFU Requests. The VFU Interval field values range from 0 to 1000 seconds (0 to 16 minutes 40 seconds). Refer to the Video Fast Update topic in the Related Topics section above for more information on this functionality.

VFU Limit ( Default = 100 requests)

As described in the VFU Interval field above, the VFU Interval and VFU limit fields are used to monitor the VFU requests that are received. If the number of requests configured in the VFU Limit field is exceeded during the time interval configured in the VFU Interval field above, the IMG 2020 will generate an event log file indicating the number of VFU Requests limit, the time of the event, and the information needed to identify the remote device sending the VFU Requests. The VFU Limit field values range from 0 to 1000 requests. Refer to the Video Fast Update topic in the Related Topics section above for more information on this functionality.