Topic Last Modified: 2011-05-16
The network adapter card of each server in the Microsoft Lync Server 2010 topology must support at least 1 gigabit per second (Gbps). In general, you should connect all server roles within the Lync Server 2010 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 Front End pool topologies, most servers should be in a
network that supports more than 1 Gbps, especially when supporting
audio/video (A/V) conferencing and application sharing.
For public switched telephone network (PSTN) integration, you can integrate by using either T1/E1 lines or SIP trunking.
Audio/Video Network Requirements
Network requirements for audio/video (A/V) in a Lync Server 2010 deployment include the following:
- The external firewall can be configured as a NAT (that is,
whether the site has only a single Edge Server deployed or has
multiple Edge Servers deployed). The internal firewall cannot be
configured as a NAT. For details about these requirements, see
External A/V Firewall and Port Requirements in the Planning
- If your organization uses a Quality of Service (QoS)
infrastructure, the media subsystem is designed to work within this
- If you use IPsec, we recommend disabling IPsec over the port
ranges used for A/V traffic. For details, see IPsec Exceptions in
the Planning documentation.
To ensure optimal media quality, do the following:
- Provision your network links to support throughput of 65
kilobits per second (Kbps) per audio stream and 500 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, Lync 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. In an
under-provisioned network, the ability of the Lync Server media
endpoints to dynamically deal with varying network conditions (for
example, temporary high packet loss) is reduced.
- For network links where provisioning is extremely costly and
difficult, you may need to consider provisioning for a lower volume
of traffic. In this scenario, you let the elasticity of the Lync
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. Also, there is 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 Lync Server media components cannot
reduce, and it is important to find and eliminate the weak
- For servers running antivirus software, include all servers
running Lync Server 2010 in the exception list in order to provide
optimal performance and audio quality. For details, see Specifying Anti-Virus
Scanning Exclusions in the Security documentation.
Conferencing Network Requirements
The bandwidth that is used to download conference content from the Internet Information Services (IIS) server depends on the size of the content that is uploaded.