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.

Chapter 1

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HP T1453-90001 manual HP-UX Vlan Tagging, Ieee 802.1Q Vlan Tag in Ethernet Frame