Another welcome feature new to Lync Server 2010 is
the capability for branch sites to continue PSTN call access in the
event of a WAN failure, making the Front End pool unavailable to the
location.
A special type of gateway called a survivable branch
appliance also serves as a registrar for users in the branch locations
so that when a WAN connection goes out, the users stay logged in to
their Lync client. For larger branch sites, a Lync Front End pool can
be created and paired with a PSTN gateway or Internet Telephony Service
Provider SIP trunk to provide resiliency.
Defining Branch Sites
The first step, whether deploying a survivable
branch appliance or a survivable branch server, is to define each
branch site within the Lync Server topology.
1. | Open the Lync Server Topology Builder and import the current topology.
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2. | Right-click Branch Office Sites and select New Branch Site.
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3. | Enter a Name for the site and, optionally, a Description.
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4. | Click Next.
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5. | Enter the City where the site is located.
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6. | Enter a State/Region where the site is located.
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7. | Enter a two-digit Country Code where the site is located.
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8. | Click Next.
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9. | Clear the check box Open the New Survivable Wizard when this wizard closes, and then click Finish. A survivable branch appliance or server can be added to the site later.
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Defining Survivable Branch Appliances and Servers
After defining each of the branch sites, the survivable branch appliances or servers must be added to the topology.
1. | Ensure the Lync Server Topology Builder is still open and a branch site has been defined.
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2. | Expand the branch site and, right-click Survivable Branch Servers, and then select New Survivable Branch Server.
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3. | Click FQDN, enter the fully qualified name of the survivable branch appliance or server, and then click Next.
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4. | Click Front-End pool and select the Front End pool associated with the branch site.
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5. | Click Edge server and select the Edge Server pool associated with the branch site.
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6. | Click Gateway FQDN or IP Address and enter the name or IP address of the gateway used for routing inbound and outbound calls with the branch site.
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7. | Click Listening Port and enter the correct port.
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8. | Click SIP Transport Protocol and select the protocol used to communicate with the gateway.
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9. | After all branch sites and survivable branch appliances have been defined, be sure to publish the topology. Figure 1
shows a sample branch site configuration. Notice that in this case the
survivable branch appliance and Mediation server names are the same.
This is because they are the same device. The PSTN gateway entered may
even be the same hardware device, but will always have a separate IP
address.
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Add the Survivable Branch Appliance to Active Directory
Each survivable branch appliance deployed needs to
have a computer account in Active Directory defined prior to being
placed in operation. Because survivable branch servers are already
domain-joined computers, these steps are not necessary.
Use the following steps when deploying only a survivable branch appliance.
1. | Log on to a computer with the Active Directory Domain Services role administration tools installed.
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2. | Open Active Directory Users and Computers.
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3. | Right-click an organizational unit, click New, and select Computer.
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4. | Enter a Computer name for the survivable branch appliance. This is just the hostname, not the fully qualified domain name.
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5. | Under User or group, click the Change button.
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6. | Enter RTCUniversalSBATechnicians, and then click OK.
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7. | Click OK.
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After staging a computer account for the survivable
branch appliance, a service principal name (SPN) must be added to the
computer account.
Use the following steps to add the SPN:
1. | Open ADSI Edit.
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2. | Right-click the ADSI Edit root node and click Connect to.
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3. | Leave the default options selected and click OK.
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4. | Expand the Default naming context and locate the survivable branch appliance computer account.
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5. | Right-click the account and select Properties.
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6. | Highlight servicePrincipalName and click Edit.
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7. | Enter HOST/<Survivable Branch Appliance FQDN> and click Add.
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8. | Click OK twice.
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Note
Normally, using the SETSPN command is the preferred
way to manage SPNs associated with domain accounts. Because the
survivable branch appliance has not joined the domain yet, the SETSPN
commands do not work properly. Instead, use ADSI Edit to configure the
appropriate SPN.
Deploying a Survivable Branch Appliance
Installation and configuration is going to vary
widely depending on the survivable branch appliance vendor and
software. Most of the steps involved are similar to the following:
1. | Physically cable the survivable branch appliance.
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2. | Configure an IP address.
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3. | Join the domain.
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4. | Enable replica of configuration.
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5. | Request and assign certificates.
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6. | |
7. | Test connectivity.
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8. | Move user accounts.
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Note
The user account used to join the survivable branch
appliance to the domain must be a member of the
RTCUniversalSBATechnicians group. This is the group selected to join
the computer to the domain when the computer account is created in
Active Directory.
Deploying a Survivable Branch Server
Installation and configuration of a survivable
branch server is identical to configuring a new Front End pool with
Mediation Server functionality.
Move Branch Users to a New Pool
After implementing the required
infrastructure for remote site survivability, the last step is to move
branch users to the new pool for their registrar service. Through
associating the branch site with a Front End pool, the users’
conferencing data is still associated with a main Front End pool and
moves only the registrar for each user.
