Export (0) Print
Expand All

Choosing a Topology

 

Topic Last Modified: 2012-08-22

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

  • Single consolidated Edge using private IP addresses for each Edge interface and a network address translation (NAT) public IP address

  • Single consolidated Edge using public IP addresses for each Edge interface

  • Scaled consolidated Edge using NAT, private IP addresses on Edge interfaces and using Domain Name System (DNS) load balancing

  • Scaled consolidated Edge using public IP addresses on Edge interfaces using Domain Name System (DNS) load balancing

  • Scaled consolidated Edge using public IP addresses and hardware load balancing

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

Summary of Edge Server Topology Options

Topology High availability NAT/Public IP address type Additional external DNS A record required for each 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

No

NAT optional / public or private IP addresses

No

No

No

Scaled Edge (DNS load balanced)

Yes

NAT optional / public or private IP addresses

Yes

Yes

No (Yes for Exchange UM with Exchange Server 2010 with SP1 or later configured to use DNS Load Balancing)

Scaled Edge (hardware load balanced)

Yes

NAT not used / public IP mandatory

No (only one per VIP)

Yes

Yes

* Failover for Exchange UM (remote user), public instant messaging (IM) connectivity, and federation with servers running Office Communications Server.

noteNote:
The NAT/Public IP required and Additional external DNS A record required for each Edge Server in the Edge pool columns pertain only to the Edge external interfaces. Single Edge and Scaled Edge (DNS load balanced) topologies can use routable public IP addresses, or can use non-routable private IP address. If you decide to use non-routable private IP addresses, you must use it on all three external interfaces. Additionally, you must configure symmetric NAT for incoming and outgoing traffic. Scaled Edge (hardware load balanced) topology must use public IP addresses.

Unlike Microsoft Office Communications Server 2007 R2, Lync Server 2010 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 Domain Name System (DNS) load balancing allows you to reduce the number of public IP address per Edge Server in an Edge pool as described in the following list:

  • Lync Server 2010 Scaled Consolidated Edge (DNS load balanced) Requires three public IP addresses for each Edge Server in an Edge pool.

  • Lync Server 2010 Scaled Consolidated Edge (hardware load balanced) Requires three public IP address for load balancer virtual IP addresses (one time requirement that does not increment as more Edge Servers are added to the pool) plus three public IP addresses per Edge Server in a pool.

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

Number of Edge Servers per pool Number of required IP addresses Lync Server 2010 (DNS load balanced) Number of required IP addresses Lync Server 2010 (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 2010 (DNS load balanced) Number of required IP addresses Lync Server 2010 (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.

  • High availability   If you need high availability, deploy at least two Edge Servers in a pool. A single Edge pool will support up to ten Edge Servers. If more capacity is required, you can deploy multiple Edge pools. As a general rule, 10% of a given user base will need external access.

  • Hardware load balancing   Hardware load balancing is supported for load balancing Lync Server 2010 Edge Servers when using publicly routable IP addresses for the Edge external interfaces. For example, you would use this approach in situations where failover is required for any of the following applications:

    • Public IM connectivity

    • External access to Exchange 2007 Unified Messaging (UM) or Exchange 2010 UM

    • Federation with companies running Microsoft Office Communications Server 2007 or Microsoft Office Communications Server 2007 R2

    These three applications will continue to operate, but they are not DNS load balancing aware and will only connect to the first Edge Server in the pool. If that server is unavailable, the connection will fail. For example, if multiple Edge Servers are deployed in a pool to handle the federated traffic load, only one access proxy actually receives traffic while the others are idle.

importantImportant:
Using DNS load balancing is recommended if you are federating with companies using Lync Server 2010. 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.
 
Was this page helpful?
(1500 characters remaining)
Thank you for your feedback
Show:
© 2014 Microsoft