HP-UX VLAN Administrator's Guide, February 2007

1. Determine the network topology affected. Either draw the affected network topology or list
it. Include all affected end stations.
See “Network Requirements” (page 19) for key network requirements related to setting up
VLANs.
2. Define the VLANs. In accordance with your requirements, determine which systems belong
to which logical groups.
See “Common VLAN Usage Scenarios ” (page 18) for common types of usage scenarios for
VLANs.
3. Assign VLAN IDs to each VLAN interface. Ensure that the assignments are consistent across
end stations and switches; otherwise, stations cannot communicate with each other. A VLAN
ID can be any number between 0 and 4094 that is used only once within that port.
NOTE: The VLAN ID is not the same as the number of VLANs supported. HP-UX supports
up to 1024 VLANs per system.
4. Determine which LAN card ports need tagged VLANs and which do not. Typically, a server
LAN card port might belong to several VLANs, whereas a desktop LAN card port can belong
to just one VLAN.
5. Assign VLAN IDs to each LAN card port on end stations and switches. Mark VLANs on
the switches as tagged or untagged according to the LAN card port to which they are
connected.
6. On servers that must belong to several VLANs, create VLANs on the corresponding LAN
card ports.
Network Requirements
You must satisfy the following requirements before setting up VLANs in a network:
• For both end stations of a VLAN to communicate, both the end-station LAN cards and the
switch ports that are connected to those LAN cards on a point-to-point link need to be VLAN
tag aware.
• For VLANs to communicate with each other, an external VLAN-aware switch or router is
required, as shown in Figure 1-5. Also, it is not possible to extend a single VLAN across a
router.
• If a hub is connected to a network of VLANs, every port on the hub must belong to the same
VLAN. Hubs do not have the ability to provide VLANs to individual ports.
VLAN awareness does not provide any benefit in a shared LAN environment (using hubs or
repeaters). In shared LAN environments, all stations see all traffic whether it is VLAN tagged
or not.
Figure 1-5 Communication Between VLANs Requires an External Router
Red VLAN
Green VLAN
LAN Card with Two
Router
External
Port A1
Port A2
Port A3
Port A4
VLANs Configured
Port-Based
Overview of VLANs 19