5.1.2. Configuring virtual networks and alias interfaces

In some cases it can be useful to fine-tune the network for special purposes. For example for Virtual Local Area Network (VLAN) technology: many organizations use it for security and network traffic separation purposes. VLANs are logically separated components of physical networks. Logical separation means that although they are on the same physical network (otherwise known as broadcast domain) hosts on separate VLANs cannot communicate with each other unless a router is set up that provides the interconnection. Routing functions for VLAN, and VLAN creation in general, are typically performed by Layer 3 Ethernet switches. Provided that VLAN-capable network cards are installed in the machine, PNS fully supports VLANs and MS provides a control for configuring it.

VLAN interfaces are named in the following manner:

ethx.n where

x

is the number of the physical interface

n

is the ID of the VLAN. The ID of the VLAN is usually a number (for example, 0 for the first VLAN of the interface, 1 for the second, and so on)

Note

If you define an interface as a VLAN interface, it cannot operate as a real, physical interface at the same time.

For example, the eth1.12 VLAN interface is the 12th VLAN interface of the eth1 physical network interface. If you define a VLAN for eth1, you cannot use eth1 as a physical interface.

Configuring VLAN and alias interfaces

Figure 5.5. Configuring VLAN and alias interfaces

Using alias interfaces allows you to configure multiple IP addresses to a physical device. Alias interfaces are named in the following manner:

ethx:n where

ethx

is the name of the corresponding physical or VLAN interface

n

is the ID of the alias interface. The ID is usually a number (for example, 0 for the first alias of the interface, 1 for the second, and so on), but it can be a more informative name too.

An alias can be defined for existing physical and VLAN interfaces.

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