The network adapter card of each server in the Office Communications Server topology must support at least 1 Gigabit per second (Gbps). In general, you should connect all server roles within the Office Communications Server topology using a low latency and high bandwidth local area network (LAN). The size of the LAN is dependent on the size of the topology:
- In Standard Edition topologies, servers should be in a network
that supports 1 Gbps Ethernet or equivalent.
- In Enterprise pool topologies, most servers should be in a
network that supports more than 1 Gbps, especially when supporting
audio/video conferencing and application sharing.
For PSTN integration, you can integrate by using either T1/E1 lines or SIP trunking.
Audio/Video Network Requirements
Key network requirements for audio/video in an Office Communications Server deployment include the following:
- In any location with multiple Edge Servers deployed behind a
load balancer, the external firewall cannot function as a network
address translator (NAT). However, in a site with only a single
Edge Server deployed, the external firewall can be configured as a
NAT. For details about this requirement, see
Requirements for External User Access.
- If your organization uses a Quality of Service (QoS)
infrastructure, the media subsystem is designed to work within this
existing infrastructure. For details, see
a QoS Environment.
- If you use IPsec, we recommend disabling IPsec over the port
ranges used for audio and video traffic. For details, see
To ensure optimal media quality, do the following:
- Provision your network links to support throughput of 45
kilobits per second (Kbps) per audio stream and 300 Kbps per video
stream, if enabled, during peak usage periods. A bidirectional
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, because 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
(latency) of 150 milliseconds (ms) under peak load. Latency is the
one network impairment that Office Communications Server media
components cannot reduce, and it is important to find and eliminate
the weak points.
Web Conferencing Network Requirements
Bandwidth utilization for meeting content downloaded from the IIS server depends on the size of the content which is uploaded. The user model defines average content sizes that have been tested. For details about the user model and other capacity planning considerations, including bandwidth considerations, see Capacity Planning.