What are HP-UX VLANs?
HP-UX VLAN Tagging
HP-UX VLAN Tagging
Network switches and end stations that know about VLANs are said to be VLAN-aware. Network switches and end stations that can interpret VLAN tags are said to be VLAN-tag-aware. HP-UX VLAN-tag-aware end stations add VLAN tags to standard Ethernet frames--a process called explicit tagging. A VLAN tag (Figure 1-2) identifies which VLAN a data frame belongs to and enables traffic from more than one VLAN to use the same switch or LAN card port (Figure 1-3).
When a VLAN-aware switch receives data from an end-station, the switch determines where the data is to go and whether the VLAN ID should be retained. If the data is to go to a device that can recognize the VLAN tag, the VLAN tag is retained. If the data is to go to a device that has no knowledge of VLANs (VLAN-unaware), the switch sends the data without the VLAN tag.
Figure 1-2 | | IEEE 802.1Q VLAN Tag in Ethernet Frame | | |
| | | | | 4 Bytes | | | | | | | |
| | | | | | | | | | | | |
| Destination | | Source | 802.1Q | | Type/Len | | Data | Frame | |
| Address | | Address | VLAN Tag | | | | | | Check | |
| | | | | | | | | | | |
| | | 2 Bytes (Tag Control Information) | | |
| | 2 Bytes | | |
| | | | | | | | | | | | |
| | Tag | User | Canonical | | VLAN ID | | | | |
| | Protocol | Priority | Format | | 12 bits | | | | |
| | ID | 3 bits | Indicator | | | | | |
| | | | | | | | |
| | | | | 1 bit | | | | | | | |
| | | | | | | | | | | | |
| | | | | | | | | | | | |
You must configure VLAN tagging on switch ports that interface to end-stations that have tagged VLANs. If a switch or end-station port is member of only a single, port-based VLAN, tagging is not required.
To transmit tagged frames, you must configure a VLAN on the end-station with a VLAN ID that matches the VLAN ID of a tagged VLAN on the switch port and the VLAN ID of a VLAN at the remote end-station. Refer to the next 3 chapters in this guide for complete details on configuring VLANs on your HP-UX end stations.
