Virtual Data Center

Virtual Data Center - What is Virtual Data Center?

A Virtual Data Center (VDC) provides the ability to create logical isolated subnets within which you can run Virtual Servers and other network services. Each of these segments provides control over the used addressing, routing and access control. You can create any number of Virtual Data Centers, in which you can have any number of subnets, providing full flexibility in designing the architecture. Network traffic within a single VDC is free.

Virtual Subnet in Virtual Data Center

A virtual subnet is a range of IP addresses assigned to a single virtual data center. Subnet addresses within a given VDC may not collide with each other. Addresses within the private address range defined in RFC 1918 are allowed:

  • 10.0.0.0/8
  • 172.16.0.0/12
  • 192.168.0.0/16

For example, creating a Virtual Subnet with the addressing of 192.168.1.0/24 will cause all services running within that subnet to have addresses assigned from that range.

When choosing the address range, please note that the following addresses are unavailable (using the example of 192.168.1.0/24):

  • network address (192.168.1.0)
  • broadcast address (192.168.1.255)
  • the first three addresses of the range (192.168.1.1, 192.168.1.2, 192.168.1.3)

Each Virtual Subnet provides the following services:

  • DHCP
  • DNS
  • Metadata Server

Additionally, optional components can be added:

  • Internet Gateway
  • NAT gateway
  • VPN gateway (in preparation)

Routing tables

Each virtual subnet has built-in routing to the addresses of all virtual machines in a given VDC (regardless of which subnets they are in). Network traffic to other addresses is managed by a routing table that can be connected to the subnet. Each routing table consists of one or more entries that specify:

  • the address range that the entry should cover (in CIDR format)
  • the Internet/NAT/VPN gateway through which traffic to that address range should be directed
If you want to create an entry that directs traffic to the Internet, use the destination address of 0.0.0.0/0


DHCP services in the virtual DC

Each Virtual Data Center has a DHCP server that automatically configures the network interfaces of Virtual Servers. The IP address assigned to the server is automatically defined at the time of its creation and falls within the range of addresses assigned to the subnet, while the host name is provided by the user or automatically generated when creating.


DNS services in the virtual DC

Each Virtual Data Center has a DNS server that provides the service of resolving domain names available on the Internet and server names connected to a given subnet.


Metadata Server services in the virtual DC

Each Virtual Data Center provides a metadata server that allows access to metadata of virtual servers via the HTTP protocol. The server is available at the address 169.254.169.254.


Virtual DC Internet Gateway Services

Virtual DC provides the ability for servers with assigned public IP address(es) to communicate with the Internet. In this case, the e24cloud infrastructure performs address translation (NAT 1:1) between the public address (visible from outside) and the internal address (visible within the VDC). The virtual server does not need to make any additional configuration changes to handle this traffic.


Virtual DC NAT Gateway Services

Virtual DC provides the ability to create a NAT gateway that provides Internet access for servers without public IP addresses. In this case, the e24cloud infrastructure performs address translation (NAT 1 to many) between the public address of the NAT gateway (visible from outside) and the internal address (visible within the VDC). Virtual servers can initiate connections to the Internet, but connections to the server from the Internet are not possible.


Limitations

Virtual DCs have the following limitations:

  • A single VDC is limited to a single location,
  • Multicast and broadcast traffic is not supported,
  • A single virtual machine can only have one network interface to the VDC.