D-Link DES-3326 User Manual - Vlan Layout
DES-3326 Layer 3 Fast Ethernet Switch User’s Guide
Web-Based Network Management
239
VLAN Layout
VLANs on the DES-3326 have rather more functions than on a
traditional layer 2 switch, and must therefore be laid-out and
configured with a bit more care. Layer 3 VLANs (VLANs with an
IP interface assigned to them) could be thought of as network links
– not just as a collection of associated end users. Further, Layer 3
VLANs are assigned an IP network address and subnet mask to
enable IP routing between them.
Layer 3 VLANs must be configured on the switch before they can
be assigned IP subnets. Further, the static VLAN configuration is
specified on a per port basis. On the DES-3326, a VLAN can
consist of end-nodes – just like a traditional layer 2 switch, but a
VLAN can also consist of one or more layer 2 switches – each of
which is connected to multiple end-nodes or network resources.
So, a Layer 3 VLAN, consisting of 4 ports, could be connected to 4
layer 2 switches. If these layer 2 switches each have 24 ports, then
the Layer 3 VLAN would contain 4 x 24 = 96 end nodes. Assigning
an IP subnet to the Layer 3 VLAN would allow wire-speed IP
routing from the WAN to each end node and between end nodes.
So, the IP subnets for a network must be determined first, and the
VLANs configured on the switch to accommodate the IP subnets.
Finally, the IP subnets can be assigned to the VLANs.
Assigning IP Network Addresses and
Subnet Masks to VLANs
The DES-3326 allows the assignment of IP subnets to individual
VLANs. Any VLAN configured on the switch that is not assigned
an IP subnet, will behave as a layer 2 VLAN and will not be
capable of IP routing – even if the switch is in IP Routing mode.