8.2.94 C-TAG (Customer-VLAN tag)

29.2443GPPInterface between the Control Plane and the User Plane nodesRelease 17TS

The C-TAG IE shall be encoded as shown in Figure 8.2.94-1. It shall contain the Customer-VLAN tag (C-TAG) as defined in IEEE 802.1Q [30].

		Bits
	Octets	8	7	6	5	4		3		2		1
	1 to 2	Type = 134 (decimal)
	3 to 4	Length = n
	5	Spare							VID		DEI		PCP
	6	C-VID value					DEI Flag		PCP value
	7	C-VID Value
	8 to (n+4)	These octet(s) is/are present only if explicitly specified

Figure 8.2.94-1: C-TAG (Customer-VLAN tag)

The following flags are coded within Octet 5:

– Bit 1 – PCP: If this bit is set to "1", then PCP Value field shall used by the receiver, otherwise the PCP Value field shall be ignored.

– Bit 2 – DEI: If this bit is set to "1", then DEI flag field shall used by the receiver, otherwise the DEI flag field shall be ignored.

– Bit 3 – VID: If this bit is set to "1", then C-VID value field shall used by the receiver, otherwise the VID Value field shall be ignored.

– Bit 4 to 8 – spare and reserved for future use.

The PCP value, DEI flag and C-VID Value are specified in IEEE 802.1Q [30] tag format.

Octet 6 / Bit 3 shall contain the most significant bit of the PCP value.

Octet 6 / Bit 8 shall be the most significant bit of the C-VID value and Octet 7 / Bit 1 shall be the least significant bit (see clause 7.1).

NOTE: The encoding of the C-Tag in PFCP differs from the encoding of the C-Tag defined in IEEE 802.1Q [30].