Lync Online Media Port Changes Offer Better Bandwidth Management

Lync Online Media Port Changes Offer Better Bandwidth Management

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Lync Online media ports are now split into three separate categories, giving you much better control over network bandwidth. This article applies to midsized business or enterprise customers with an internal proxy or firewall server.

Author: Rob Pittfield, Microsoft Senior Service Engineer

Contributor: Patrick Kelley

Technical Reviewers: Darrin Hanson | Francois Doremieux | Thomas Laciano

Published: June 26, 2013

Updated: July 3, 2013

Product version: Lync Online

Lync Online media ports are now split into three separate categories, giving you much better control over network bandwidth, as shown in Table 1 below:

Table 1. Lync Online media ports separated into three categories
















Application sharing and file transfer

This enables you to manage the flows differently on your network, for example giving a higher network priority to audio or video packets using Differentiated Services Code Point (DSCP).

You can achieve this either through configuration of your network elements to apply DSCP tags to traffic coming from the relevant ports, or by applying DSCP tags to the packets at the desktop using Quality of Service (QoS) group policies.

The result can be a smoother Lync peer-to-peer (and possibly multiparty conferencing) conversation experience during times of heavy use of your network.

Please note that this applies only to client ports. Server ports (specifically Lync Online edge ports, because AVMCU ports are not directly visible) remain unchanged, covering the full 50,000-59,999 port range without segmentation by media type.

For traffic from clients on your network to server, traffic prioritization, if desired, should be applied either at desktop or at first network element based on source port.

For traffic from server to clients on your network, traffic prioritization, if desired, should be applied at the ingress point based on destination port.


  • QoS group policies work with only client machines running Windows 7 or Windows 8.
  • DSCP tags have no effect on media traffic on the internet, may be reset as they travel outside your network, and may not be honored by other parties (such as federated Lync users).
  • The Lync Online service doesn’t add DSCP tagging or perform prioritization on existing DSCP Tagging.
  • Because multiparty conferencing traffic travels from your network to the Microsoft datacenter on networks that do not honor DSCP tags, traffic prioritization only occurs on the portion of the path that you control on your network. This may or may not result in improvements to the conversation experience.

For details, see Configuring Quality of Service Policies for Clients Running on Windows 7 or Windows 8.

Further, we are planning to eventually split out the Application sharing and File Transfer ports so that traffic can be prioritized independently also.

About the Author

Rob Pittfield is a Dedicated Premier Field Engineer for Microsoft Lync Server 2010 and Microsoft Office Communications Server 2007 R2. He works with enterprise customers, helping them get Microsoft Lync 2010 and Office Communications Server running smoothly and to their expectations.

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  • Rob - will you be updating the TechNet QoS Policy page?

  • Hi Steve,

    That link shows sample port ranges and isn't related to what Lync Online is doing so we won't be updating that page.



  • this post is helpful for me.