5.7.5.2 UE Derived QoS Rule

The UE derived QoS rule contains following parameters:

• One UL Packet Filter (in the Packet Filter Set as defined in clause 5.7.6);
• QFI;
• Precedence value (see clause 5.7.1.9).

Upon receiving DL packet, one UL Packet Filter derived from the received DL packet as described in this clause is used to identify a UE derived QoS rule within a PDU Session.

For PDU Session of IP type, the UL Packet Filter is derived based on the received DL packet as follows:

• When Protocol ID / Next Header is set to TCP or UDP, by using the source and destination IP addresses, source and destination port numbers and the Protocol ID / Next Header field itself.
• When Protocol ID / Next Header is set to UDP, if the received DL packet is UDP-encapsulated IPSec protected packet, by using the source and destination IP addresses, source and destination port numbers, the Security Parameter Index and the Protocol ID / Next Header field itself. In this case, if an uplink IPSec SA corresponding to a downlink IPSec SA of the SPI in the DL packet exists and the SPI of the uplink IPSec SA is known to the NAS layer, then the UL Packet Filter contains an SPI of the uplink IPSec SA.
• When Protocol ID / Next Header is set to ESP, by using the source and destination IP addresses, the Security Parameter Index and the Protocol ID / Next Header field itself. If the received DL packet is an IPSec protected packet and an uplink IPSec SA corresponding to a downlink IPSec SA of the SPI in the DL packet exists and the SPI of the uplink IPSec SA is known to the NAS layer, then the UL Packet Filter contains an SPI of the uplink IPSec SA.

NOTE 1: In this Release of the specification for PDU Sessions of IP type the use of Reflective QoS is restricted to service data flows for which Protocol ID / Next Header is set to TCP, UDP or ESP.

NOTE 2: The UE does not verify whether the downlink packets with RQI indication match the restrictions on Reflective QoS.

NOTE 3: How to determine the received DL packet is UDP-encapsulated IPSec protected packet is defined in RFC 3948 [138]. UDP encapsulation for ESP is used when a NAT is detected and there can be different Security Parameter Indexes within the same IP-tuples.

NOTE 4: Despite the indication of support for Reflective QoS, the UE might not be able to derive QoS Rules for ESP IPSec packets and UDP-encapsulated IPSec packets, if uplink IPSec SA corresponding to a downlink IPSec SA of the SPI in the DL packet exists and the SPI of the uplink IPSec SA is not known to the NAS layer.

For PDU Session of Ethernet type the UL Packet Filter is derived based on the received DL packet by using the source and destination MAC addresses, the Ethertype on received DL packet is used as Ethertype for UL packet. In the case of presence of IEEE Std 802.1Q [98], the VID and PCP in IEEE Std 802.1Q [98] header(s) of the received DL packet is also used as the VID and PCP field for the UL Packet Filter. When double IEEE Std 802.1Q [98] tagging is used, only the outer (S-TAG) is taken into account for the UL Packet Filter derivation.

NOTE 5: In this Release of the specification for PDU Sessions of Ethernet type the use of Reflective QoS is restricted to service data flows for which 802.1Q [98] tagging is used.

The QFI of the UE derived QoS rule is set to the value received in the DL packet.

When Reflective QoS is activated the precedence value for all UE derived QoS rules is set to a standardised value.