Network Requirements

Audio Video Requirements

The following section summarizes some key network requirements for audio/video in an Office Communications Server deployment:

• If you plan to deploy an A/V Edge Server, a publicly routable IP address is required on the external interface of the A/V Edge Server. For more information about this requirement, see Publicly Routable IP Address for External A/V Access.

• If you anticipate a high volume of audio/video traffic or experience packet loss after you deploy, you should optimize the network interface card to accommodate the A/V traffic. Refer to any of the following documents for details: the Microsoft Office Communications Server 2007 Edge Server Deployment Guide, or the Microsoft Office Communications Server 2007 Standard Edition Deployment Guide, Microsoft Office Communications Server 2007 Enterprise Edition Deployment Guide.

• If your organization uses a Quality of Service (QoS) infrastructure, the media subsystem is designed to work within this existing infrastructure. See Appendix A: Implementing in a QoS Environment, for more information.

• If you use IPSec, we recommend disabling IPSec over the port ranges used for audio and video traffic, See Appendix B: Disabling IPSec for more information.

To ensure optimal media quality, do the following:

• Provision your network links to support throughput of 45 Kbps per audio stream and 300 Kbps per video stream, if enabled, during peak usage periods. A bi-directional audio or video session consists of two streams.

• To cope with unexpected spikes in traffic above this level and increased usage over time, Office Communications Server media endpoints can adapt to varying network conditions and support loads of three times the throughput (see previous paragraph) for audio and video while still retaining acceptable quality. However, do not assume that this adaptability will support an under-provisioned network as this will reduce the ability of the Office Communications Server media endpoints to dynamically deal with varying network conditions, such as temporary high packet loss.

• For network links where provisioning is extremely costly and difficult, you may be forced to consider provisioning for a lower volume of traffic and let the elasticity of the Office Communications Server media endpoints absorb the difference between that traffic volume and the peak traffic level, at the cost of some reduction in the voice quality, but also of a decrease in the headroom otherwise available to absorb sudden peaks in traffic.

• For links that cannot be correctly provisioned in the short term, for example a site with very poor WAN links, consider disabling video for certain users.

• Provision your network to ensure a maximum end to end delay of 150 ms under peak load. Delay is the one network impairment that Office Communications Server media components cannot reduce, and it is important to find and eliminate the weak points.

For additional information about how Microsoft provides an optimal quality of experience, see Microsoft Quality of Experience at the Microsoft Web site: https://r.office.microsoft.com/r/rlidOCS?clid=1033&p1=MSQoE..

Web Conferencing Requirements

The bandwidth utilization for a standalone Web Conferencing Server in an expanded pool configuration in terms of average bandwidth per user for an application sharing session is approximately 14 Kbps. Bandwidth utilization for meeting content download from the IIS server is dependent upon the size of the content which is uploaded. The user model defines average content sizes which have been tested.