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

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.

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