I have a management network that uses two physical switches, and each switch uses a
different VLAN and IP subnet. I would create a single logical network for my
management network and then a separate site for each of the network configurations,
one for each VLAN and IP subnet pair.
A network site can be configured with just an IP subnet, just a VLAN, or an IP
subnet/VLAN pair. You need to configure IP subnets for a site only if SCVMM will be
statically assigning IP addresses to the site. If DHCP is present, no IP subnet
configuration is required. If VLANs are not being used, a VLAN does not need to be
configured. If DHCP is used in the network and VLANs are not used, you do not have
to create any network sites.
After the sites are defined within a logical network, IP pools can be added to the IP
address subnet that’s defined, which enables SCVMM to configure virtual machines
with static IP addresses as the virtual machines are deployed. If DHCP is used in the
network, there is no need to configure IP pools in SCVMM or even specify the IP
subnet as part of the site configuration. DHCP would be leveraged for the IP
assignment, but if you don’t have DHCP, then creating the IP pool allows SCVMM to
handle the IP assignment for you.
The IP assignment is achieved by modifying the Sysprep answer file with the IP
address from the SCVMM IP pool as the virtual machine template is deployed. When
the virtual machine is deleted, SCVMM reclaims the IP address into its pool. Even if
DHCP is primarily used in the network, if you are using features such as load
balancing as part of a service, SCVMM has to be able to allocate and track that IP
address, which requires the configuration of an IP pool. If no IP pool is created for a
network site, SCVMM configures any virtual machines to use DHCP for address
allocation. Both IPv4 and IPv6 are fully supported by SCVMM (and pretty much any
Microsoft technology, because a Common Engineering Criteria requirement for all
Microsoft solutions is support for IPv6 at the same level as IPv4).
At a high level, this means the logical network models your physical network and
allows the subnet and VLANs to be modeled into objects and then scoped to specific
sites, which can also include static IP address pools for allocation to resources such as
virtual machines and load-balancer configurations. This is shown in Figure 3.14, with
a management logical network that has two network sites, Dallas and Houston, along
with the IP subnet and VLAN used at each location. For Dallas, an IP pool was also
created for the network site to enable static IP configuration. Houston uses DHCP
because no IP pool was created for the Houston network site within the logical
network.