Topic Last Modified: 2013-02-21

When you choose a topology, you can use one the following supported topology options:

Note:
Unless otherwise noted, if you have experience with Microsoft Lync Server 2010, you will find the guidance here is largely unchanged.
Important:
The internal Edge interface and external Edge interface must use the same type of load balancing. You cannot use DNS load balancing on one Edge interface and hardware load balancing on the other Edge interface.

The following table summarizes the functionality available with the supported Microsoft Lync Server 2013 topologies. The column headings indicate the functionality available for a given Edge configuration option. Using the Scaled Edge (DNS load balanced) option as an example, you can see that it supports high availability, can use non-routable private IP addresses (with NAT) or routable public IP addresses assigned to the Edge external interfaces, and reduces cost because a hardware load balancer is not required.

Edge failover scenarios supported with DNS Load Balancing are Lync-to-Lync point-to-point sessions, Lync conferencing sessions, Lync-to-PSTN sessions and Office 365. Edge failover scenarios that do not benefit from DNS Load Balancing are failover for remote user Exchange Unified Messaging (UM) (prior to Exchange 2010 SP1), public instant messaging (IM) connectivity, and federation with servers running Office Communications Server.

Summary of Edge Server Topology Options

Topology High availability Additional DNS A records required for external Edge Server in the Edge pool Edge Failover for Lync-to-Lync sessions Edge Failover for Lync-to-Lync EUM/PIC/OCS Federation sessions

Single Edge using NAT

No

No

No

No

Single Edge using Public IP

No

No

No

No

Scaled Edge (DNS Load Balanced) using NAT

Yes

Yes

Yes

*

Scaled Edge (DNS Load Balanced) using Public IP

Yes

Yes

Yes

*

Scaled Edge Hardware load balanced)

Yes

No (one DNS A record per VIP)

Yes

Yes

* Failover for public instant messaging (IM) connectivity, and federation with servers running Office Communications Server is not available with DNS load balancing. Exchange UM (remote user) failover using DNS load balancing requires Exchange Server 2010 SP1 or newer.

Note:


Single Edge and Scaled Edge (DNS load balanced) topologies can use:
  • Routable public IP addresses

  • Non-routable private IP address if symmetric network address translation (NAT) is used

    Note:
    If you use public IP address or private IP address with NAT, you will still use the same number of IP addresses based on your configuration choice in Topology Builder. You can configure the Edge Server to use a single IP address with distinct ports per service, or use distinct IP addresses per service, but use the same port (by default, TCP 443).
If you decide to use non-routable private IP addresses with NAT:
  • You must use routable private IP addresses on all three external interfaces

  • You must configure symmetric NAT for incoming and outgoing traffic

Scaled Edge (hardware load balanced) topology must use public IP addresses.

Lync Server 2013 supports placing Access, Web Conferencing, and A/V Edge external interfaces behind a router or firewall that performs network address translation (NAT) for both single and scaled consolidated Edge Server topologies.

Using NAT for all Edge external interfaces requires the use of DNS load balancing. When compared to using hardware load balancers, using DNS load balancing without NAT allows you to reduce the number of public IP address per Edge Server in an Edge pool as described in the following list:

IP Address Requirements for Scaled Consolidated Edge (IP Address per role)

Number of Edge Servers per pool Number of required IP addresses Lync Server 2013 (DNS load balanced) Number of required IP addresses Lync Server 2013 (hardware load balanced)

2

6

3 (1 per VIP) + 6

3

9

3 (1 per VIP) + 9

4

12

3 (1 per VIP) + 12

5

15

3 (1 per VIP) + 15

IP Address Requirements for Scaled Consolidated Edge (Single IP address for all roles)

Number of Edge Servers per pool Number of required IP addresses Lync Server 2013 (DNS load balanced) Number of required IP addresses Lync Server 2013 (hardware load balanced)

2

2

1 (1 per VIP) + 2

3

3

1 (1 per VIP) + 3

4

4

1 (1 per VIP) + 4

5

5

1 (1 per VIP) + 5

The primary decision points for topology selection are high availability and load balancing. The requirement for high availability can influence the load balancing decision.

Important:
Using DNS load balancing is recommended if you are federating with companies using Lync Server 2010 and Microsoft Office 365. Be aware that there are significant performance impacts if most of your federated partners are using Office Communications Server 2007 or Office Communications Server 2007 R2.