1. Domain Name System
Lync
Server utilizes DNS as the method for resolving names to IP addresses
and for identifying servers that provide specific services.
Although there are various
ways to install and configure DNS, the most straightforward and
complete process involves invoking the Add Roles Wizard and the
subsequent Configure a DNS Server Wizard. The process detailed in this
section illustrates the installation of a standard zone. Multiple
variations of the installation are possible, but this particular
scenario is illustrated to show the basics of DNS installation.
Install and Configure DNS on Windows Server 2008 R2
Installation of DNS on
Windows Server 2008 R2 is straightforward, and no reboot is necessary.
To install and configure the DNS service on a Windows Server 2008 R2
computer, follow these steps:
1. | Launch Server Manager.
|
2. | Select the Roles node and click the Add Roles link.
|
3. | Click Next on the Before You Begin page.
|
4. | Select the DNS Server role check box and click Next.
|
5. | Click Next on the Introduction to DNS Server page.
|
6. | Click Install on the Confirmation page to install the DNS role.
|
7. | Click Close to exit the Add Roles Wizard.
|
The DNS role is installed
on the Windows Server 2008 R2 server, but it has not been configured. To
configure the role, execute the following steps:
1. | Launch Server Manager.
|
2. | Expand the roles, DNS server, DNS nodes, and then select the DNS server name.
|
3. | Select Action, Configure a DNS Server.
|
4. | On the Welcome page for the Configure a DNS Server Wizard, click Next to continue.
|
5. | Select Create Forward and Reverse Lookup Zones (Recommended for Large Networks), and then click Next.
|
6. | Select Yes, Create a Forward Lookup Zone Now (Recommended), and then click Next.
|
7. | Select the type of zone to be created—in this case, choose Primary Zone—and then click Next. If the server is a writable domain controller, the Store the Zone in Active Directory check box is available.
|
8. | If you are storing the zone in Active Directory, select the replication scope, and then click Next.
|
9. | Type the FQDN of the zone in the Zone Name box, and then click Next.
|
10. | At
this point, if creating a non–AD–integrated zone, you can create a new
zone text file or import one from an existing zone file. In this case,
choose Create a New File with This File Name and accept the default. Click Next to continue.
|
11. | The
subsequent page allows a zone to either accept or decline dynamic
updates. For this example, enable dynamic updates by selecting the Allow Both Nonsecure and Secure Updates option button, and then clicking Next.
|
12. | The next page allows for the creation of a reverse lookup zone. Here, select Yes, Create a Reverse Lookup Zone Now, and then click Next.
|
13. | Select Primary Zone for the reverse lookup zone type, and then click Next.
|
14. | If storing the zone in Active Directory, select the replication scope, and then click Next.
|
15. | Accept the default IPv4 Reverse Lookup Zone, and then click Next.
|
16. | Type the network ID of the Reverse Lookup Zone, and then click Next.
Note
The network ID is
typically the first set of octets from an IP address in the zone. If a
Class C IP range of 192.168.3.0/24 is in use on a network, you enter the
values 192.168.3.
|
17. | Again,
if creating a non–AD–integrated zone, you are offered the option to
create a new zone file or to utilize an existing file. For this example,
choose Create a New File with This File Name, and then click Next to continue.
|
18. | Again, you are presented the option for dynamic updates. For this example, select Allow Both Nonsecure and Secure Updates, and then click Next to continue.
|
19. | The
next page deals with the setup of forwarders, which are normally used
when only part of DNS is delegated to Active Directory. In this example,
choose No, It Should Not Forward Queries, and then click Next to continue.
|
20. | The final window displays a summary of the changes that are made and the zones that are added to the DNS database. Click Finish to finalize the changes and create the zones.
|
DNS Records Lync Server Uses
Lync Server utilizes DNS
for several purposes. Not only do traditional hostname-to-IP address
lookups occur, Lync Server utilizes specialized DNS records to identify
particular services much like Active Directory does. Lync Server is even
able to use DNS round robin to provide load balancing between sites.
Some record examples include
Lync Server requires
registration of hostnames of servers as A records. Administrators
implementing the DNS load-balancing features of Lync Server are required
to specify the server FQDN and the cluster FQDN using the same IP
address for each server in the cluster and A records for all clusters
that contain an Enhanced registrar. For example:
| ClusterNode1.companyabc.com | A | 10.1.1.2 |
| RegistrarCluster.companyabc.com | A | 10.1.1.2 |
| ClusterNode2.companyabc.com | A | 10.1.1.3 |
| RegistrarCluster.companyabc.com | A | 10.1.1.3 |
The more unusual DNS
records used by Lync Server are SRV records. These are used to identify
resources of a particular type that are either providing a specific
service or that are in a particular location. This is where the
subdomains come into play. For example:
_sipinternal._tcp.companyabc.com
SRV records hold additional information, such as
Domain: Companyabc.com
Service: _sipfederationtls
Protocol: _tcp
Priority: 10
Weight: 100
Port number: 5061
Host offering this service: FQDN of host
This
enables a client to ask DNS where to find a host providing a specific
service, and DNS can return one or more answers. By using Priority and
Weight, one can enforce a behavior of how loads are shared or directed.
2. Network Dependencies
Lync Server, a product that
provides voice, video, and text services over a network, has many
dependencies on the network to provide functionality. Although concepts
such as connectivity and sufficient bandwidth are obvious, other
dependencies exist, including services such as DHCP, network site
definitions, and configuration of specific features on the network
switches.
Supporting Lync Server with DHCP
Although
soft clients inherit their connectivity from the host they are
connected to, specialized devices such as VoIP desk phones are likely
managed centrally by the Lync Server administrator. Traditionally, these
devices are configured via DHCP to allow them to connect properly and
to let the device know where to look for firmware of software updates.
Microsoft recommends several DHCP options for use with Communicator
Phone Edition devices. These are
Option 43— CS Pool Certificate Provisioning Service URL—Specifies the internal (Uniform Resource Locator) URL in the form https://CSWebPoolDFQDN:443/CertProv/CertProvisioningService.svc.
Option 120—
FQDN for the CA Pool Registrar—Specifies the pool fully qualified
domain name for the pool that acts as the first logon server for the
device, usually a Director pool.
Option 43—
VLAN ID—Allows the configuration of a Virtual Local Area Network (VLAN)
ID. Do not use this if you use Link Layer Discovery Protocol
(LLDP)-enabled switches for providing VLAN IDs.
Option4— TimeServer—Points the device to a time server to keep it in sync with other systems.
Segregation of Traffic
To
ensure the best audio quality, it is highly recommended that
administrators separate VoIP traffic from other network traffic by
placing voice devices on a VLAN that is dedicated to voice functions.
Similarly, users with USB-based devices should connect to a wired
network rather than a wireless network. By keeping phone devices on a
segregated VLAN, it is easier to layer services such as Quality of
Service (QoS) onto the network segment to ensure the best possible voice
quality for end users. It also makes it simpler to monitor devices
because they are logically grouped at the network level.
Switch Configurationss
Because IP phones running
the Communicator 2010 Phone Edition support LLDP-MED (Link Layer
Discovery Protocol-Media Endpoint Discovery) and PoE (Power over
Ethernet), you have to utilize switches that support IEEE802.1AB and
ANSI/TIA-1057 to take advantage of LLDP-MED. Similarly, to utilize PoE,
the switches must support PoE802.3AF or 802.3at.
If using LLDP-MED, be sure to set LLDP-MED network policy to the correct voice VLAN ID.
Defining Network Sites
Not unlike Active Directory or
Exchange, Lync Server needs to define network sites and associated
subnets to make decisions about where to access a resource or how to
route a call. All subnets in a network should be defined and associated
with a correct network site in Lync Server. This is easily handled by a
simple comma-separated value file and the Lync Server cmdlets in
PowerShell. For example, the CSV file might be called subnet.csv and
contain
IPAddress, mask, description, NetworkSiteID
10.1.1.0, 24, "NA:Subnet in Dublin", Dublin
10.1.2.0, 24, "NA:Subnet in Lompoc", Lompoc
10.1.3.0, 24, "NA:Subnet in Ocean Springs", Ocean_Springs
10.1.4.0, 26, "EU:Subnet in London", London
These values can be easily imported into the Lync Server network’s definitions via this command:
import-csv subnet.csv | foreach {New-CSNCSSubnet $_.IPAddress -MaskBits $_.mask
–Description $_.description -NetworkSiteID $_.NetworkSiteID}
This
script can be scheduled to run regularly, and when new sites or subnets
are added to the network, the csv file is updated and the script keeps
the network definitions current.
