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Capacity planning

The capacity of each Conferencing Node in your Pexip Infinity deployment - in terms of the number of connections* that can be handled simultaneously - depends on a variety of factors including:

* A connection can be a call or presentation from an endpoint to a Virtual Meeting Room or Virtual Auditorium, a backplane between Conferencing Nodes, or a call into or out of the Pexip Distributed Gateway. In this context, a connection is analogous to a port.

The following sections explain each of these factors. For some comprehensive examples showing how these different factors can combine to influence capacity, see Resource allocation examples.

Server capacity

The capacity and configuration of the server on which the Conferencing Node is running will impact the number of calls that can be handled. This is influenced by a number of factors, including:

  • processor generation
  • number of cores
  • processor speed
  • hypervisor
  • BIOS settings

For more information, see Server design recommendations and Example Conferencing Node server configurations.

Types of call

The type of call (HD, audio-only and so on) affects the amount of resource required to handle the call.

A single HD call requires roughly:

  • half the resources of a Full HD call
  • twice the resources of an SD call, or
  • 12 times the resources of an audio-only call.

On startup, each Conferencing Node runs an internal capacity check. This capacity is translated into an estimated maximum number of HD, SD or audio-only calls, and can be viewed on the status page (Status > Conferencing Nodes) for each Conferencing Node. The status also shows the current media load on each Conferencing Node as a percentage of its total capacity.

When a Conferencing Node receives a call, it selects the node with the most available capacity in its location to handle the media for that conference. For more information, see Handling of media and signaling.

Backplane reservation

Each conference instance on each 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.

For some reservation examples, see Resource allocation examples.

Gateway calls

Gateway calls (person-to-person calls) require sufficient capacity for both the inbound leg and the outbound leg. In general, this means that each gateway call consumes resources equivalent to two connections.

Non-distributed gateway calls involving only SIP or H.323 clients do not use any additional ports. However, in other scenarios, additional ports may be used:

  • Distributed gateway calls (where the outbound leg is on a different Conferencing Node to the inbound leg) consume backplane ports — thus 1 HD video + 1 backplane for participant A plus 1 HD video + 1 backplane for participant B. This typically occurs when calling registered endpoints (where the outbound call to the registered endpoint will originate from the node the endpoint is registered to), or when using Call Routing Rules with an Outgoing location set to something other than Automatic.
  • For non-distributed gateway calls involving a Lync / Skype for Business client, a backplane is reserved in case the Lync/SfB user starts presenting (as the RDP/VbSS presentation stream could connect to any Conferencing Node due to DNS). Each presentation stream counts as 1 HD port. Thus if the incoming RDP/VbSS call lands on the same node as the video call then the resource usage is equivalent to 3 HD ports (2 video + 1 presentation). If the RDP/VbSS call lands on a different node to the video call then the resource usage for the call is equivalent to 5 HD ports (2 video + 2 backplane + 1 presentation).
  • For calls between SIP/H.323 clients and an Infinity Connect WebRTC client, 1 port is reserved for a full motion presentation stream (so these calls will consume 3 HD ports). A call between 2 WebRTC clients will also reserve 3 HD ports (2 video + 1 full motion presentation) but could also use 1 extra port (making 4 in total) if the receiving client chooses to receive the presentation stream in full motion.


The total number of concurrent calls that can be made in your deployment (regardless of whether those calls are HD, SD or audio-only) is limited by your license. For more information, see Pexip Infinity license installation and usage.