A number of different types of connections to Transcoding Conferencing Nodes are required for a conference to take place, or for a gateway call to be made.
A connection can be a call or presentation from an endpoint to a Virtual Meeting Room or Virtual Auditorium, a backplane between Transcoding Conferencing Nodes, or a call into or out of the Pexip Distributed Gateway. In this context, a connection is analogous to a port.
When a connection is proxied via a Proxying Edge Node, the proxying node also consumes connection resources in order to forward the media streams on to a Transcoding Conferencing Node. A transcoding node always consumes the same amount of connection resources regardless of whether it has a direct connection to an endpoint, or it is receiving the media streams via a proxying node.
Each connection to a Transcoding Conferencing Node requires a certain amount of resource, or capacity.
In general, when compared to a single high definition HD 720p call:
- a Full HD 1080p call uses twice the resource
- a standard definition SD call uses half the resource
- an audio-only call uses one twelfth of the resource.
A WebRTC call using the VP9 codec will use around 50% more resource, so VP9 at 720p uses the equivalent of 1.5 HD resources, and VP9 at 1080p uses the equivalent of 3 HD resources.
The following rules determine how hardware resources are allocated and consumed by conference and gateway calls in a Pexip Infinity deployment.
- Each HD participant uses one HD connection, except for VP9 participants who use 1.5 HD connections.
- Standards-based endpoints (SIP or H.323) do not require an additional connection when sending or receiving presentation. Presentation is sent and received using the call connection.
- Skype for Business / Lync participants each require one additional HD connection when sending or receiving presentation.
WebRTC VP8 participants:
- require one additional HD connection when sharing their screen (regardless of their client's Screensharing quality setting), and
- require one additional HD connection when receiving full motion presentation.
WebRTC VP9 participants:
- require 1.5 additional HD connections when sharing their screen (regardless of their client's Screensharing quality setting), and
- require 1.5 additional HD connections when receiving full motion presentation.
Each conference instance on each Transcoding Conferencing Node reserves 1 HD connection for a backplane, to allow the conference to become geographically distributed if required. The exceptions to this are:
- Deployments with a single Conferencing Node. In such cases, no backplanes will ever be required, so capacity is not reserved.
- Conferences that are audio-only (in other words, where the conference has its Conference capabilities set to Audio-only). In such cases, capacity equivalent to one audio connection is reserved for the backplane.
- Deployments with 1080p enabled. In such cases, backplanes reserve 1 Full HD connection of capacity, approximately double that of an HD connection.
- Only one backplane connection is used for each conference on each Transcoding Conferencing Node, regardless of the number of other transcoding nodes that are involved in the conference. Note that on the Administrator interface, backplanes are displayed as unidirectional, so a single link between two nodes is shown with two backplanes, one in each direction. Likewise, a conference between three nodes is shown with six backplanes. However, for resource allocation purposes each node would require just one backplane connection.
Pexip Infinity always tries to optimize gateway calls:
- A gateway call does not reserve resource for a backplane, but will use one if required (for example, if the participants are connected via different Transcoding Conferencing Nodes).
If both of the participants in a gateway call are connected to the same node, and at least one of the participants is either a WebRTC VP8
*WebRTC connections are assumed to be using the VP8 codec. VP9 calls will consume around 1.5 times the resource for calls and for presentation streams (i.e. 1.5 HD for 720p, and 3 HD for 1080p).client or a Skype for Business / Lync client, and there is currently no presentation being sent by either participant, Pexip Infinity reserves 1 HD connection on the node to which the participants are connected. This is in case either participant starts sending presentation and that presentation is handled on a different node to the node to which the participants are connected, thus requiring a backplane to be created between the two nodes.
- If the gateway call is to a Hangouts Meet meeting, an additional resource is reserved by Pexip Infinity regardless of the client making the call. This is to provide future support for a separate presentation stream in calls with Hangouts Meet. However, for the current release of Pexip Infinity this resource will not be used because the presentation stream replaces the main video stream.
- If the gateway call is to a Microsoft Teams meeting, the equivalent of 1.5 HD connections is required for the connection between Pexip Infinity and the Microsoft Teams meeting. However, no additional resources are reserved by Pexip Infinity for presentation to or from the Microsoft Teams meeting, regardless of the client making the call. This is because presentation and main share the same connection in calls to Microsoft Teams.
- SD quality can be enforced by reducing the bandwidth of a service or gateway call to 960 kbps or less. Pexip Infinity will consume less resource per-call, however, it will still reserve an HD connection for the backplane.
- Note that if an API participant is the first participant to join a conference, it will reserve a backplane for the conference.
When a connection is proxied via a Proxying Edge Node, the proxying node also consumes connection resources in order to forward the media streams on to a Transcoding Conferencing Node.
A proxying node uses approximately the equivalent of 3 audio-only resources to proxy a video call (of any resolution), and 1 audio-only resource to proxy an audio call.
See Pexip Infinity license installation and usage for full information about how call licenses are consumed.