5G NR QoS Principles
SMF requests PCF to give the SM policy for the PDU session.
After that SMF will get the SM Policy Decision from PCF.
After receiving these policies, SMF will:
1. Create a SDF and QOS flow bind.
2. Determine the control rule information used by UPF according to PCC rules and send to UPF.
3. Determine the QoS rules and send to UE for Uplink service.
4. Determine the QoS Profile and send to RAN for gNB to perform QoS control.
5G NR packet filter set
Packet Filter Set is used in QoS rule and PDR to identify one or more packet flows.
The Packet Filter Set may contain one or more Packet Filter(s). Every Packet Filter is applicable for the DL direction, the UL direction or both directions.
A packet filter contains 5 tuple {Source IP, Source Port, Type of Transport (TCP/UDP), Destination IP, Destination Port}
The data packets that meet the same matching characteristics will be placed in the same data stream.
There are 2 types of packet filter set:
1. IP Packet Filter Set
> Source/destination IP address or IPv6 prefix.
> Source / destination port number.
> Protocol ID of the protocol above IP/Next header type.
> Type of Service (TOS) (IPv4) / Traffic class (IPv6) and Mask.
> Flow Label (IPv6).
> Security parameter index.
> Packet Filter direction.
2. Ethernet Packet Filter Set
> Source/destination MAC address.
> Ethertype as defined in IEEE 802.3 [131].
> Customer-VLAN tag (C-TAG) and/or Service-VLAN tag (S-TAG) PCP/DEI fields
> IP Packet Filter Set, in the case that Ethertype indicates IPv4/IPv6 payload.
> Customer-VLAN tag (C-TAG) and/or Service-VLAN tag (S-TAG) VID fields
> Packet Filter direction.
QoS Flow Binding
> WKT UPF will receive multiple and different types of data packets from N6 interface.
> Those packets will go through UPF filter sent by SMF SDF one by one.
> UPF maps the SDF to the QoS flow according to the rules given by SMF.
> This step of mapping SDF to QoS flow is QoS Flow Binding.
> If there are any data packets that does not find suitable SDF, then UPF will trigger the SMF to create a new QoS flow.
Service data flow template
A set of service data flow filters in PCC rule are called as Service Data Flow Template.
A service data flow refers to the group of packet flow from UPF and matching the service data flow template.
Source TS 23 501