Topic Last Modified: 2011-03-22

Microsoft Lync Server 2010 communications software supports the following IP and networking protocols:

• IP Protocols. Lync Server 2010 supports only IP version 4 (IPv4). It does not support IP version 6 (IPv6).
  
  

  Note:
  Lync Server 2010 can function in a network with dual IP stack enabled.

• SIP Transport Protocols. Generically, SIP can use at least three transport types: User Datagram Protocol (UDP), Transmission Control Protocol (TCP), and Transport Layer Security (TLS). In the default SIP transport configuration, TLS runs over TCP. TLS is used within the Lync Server network. At the edge of the network, Lync Server can interoperate over TCP. Lync Server 2010 does not support UDP for SIP transport because it doesn’t meet the minimum standards for enterprise communications security, reliability, and scalability. For details, see the Office Communications Server team blog article, "To UDP, or not to UDP, that is the question," at http://go.microsoft.com/fwlink/?LinkId=185369.
  
  

  Note:
  The content of each blog and its URL are subject to change without notice.