Using DPDK APIs as the IF between UPF-C and UPF-U

1 . x Using DPDK APIs as the I/F Between UPF-C and UPF-U BARAK PERLMAN & BRIAN KLAFF ETHERNITY NETWORKS 

2 . 5G System Architecture • UPF is a 5G architecture NSSF NEF NRF PCF UDM AF data plane element Nnssf Nnef Nnrf Npcf Nudm Naf • Replaces the user plane of SGW and PGW Nausf Namf Nsmf • Control and User Plane AUSF AMF SMF SCP Separation (CUPS) N2 N4 User Plane Function UE (R)AN N3 UPF N6 DN User Equipment (Radio) Access Network Data Network N9 2 

3 . Accelerating UPF in 5G Access Endpoints Core Edge • Many operators are now moving UPF to the edge AMF • Optimal UPF at aggregation N1 N2 N11 locations • Used for local breakout N4 PFCP SMF • Partial/complete data plane offloading over FPGA-based SmartNICs N3 N6 UPF UPF UPF SmartNIC • Programmable Acceleration (R)AN Data Network • Scalable •SMF – Session Management Function • Open APIs UE •UPF – User Plane Function •PFCP – Packet Forwarding Control Protocol 3 

4 .Packet Processing Flow in UPF PDR – Packet Detection Rule FAR – Forwarding Action Rule QER – QoS Enforcement Rule URR – Usage Reporting Rule BAR – Buffering Action Rule MAR – Multi-Access Rule 4 

5 . Separation of UPF to UPF-C and UPF-U SMF N4 PFCP VM/container #m UPF-C DPDK Hypervisor UPF x86 Server PCIe Access N3 GTP IP N6 Data UPF-U Network PM counters Network 25G/40G/100G 25G/40G/100G SmartNIC 5 

6 . Partial Offload SMF N4 PFCP VM/container #m UPF-C PM Counters Control DPDK Packets Hypervisor UPF x86 Server PCIe N3 GTP UPF-U IP N6 Data Access Network Network 25G/40G/100G 25G/40G/100G SmartNIC 6 

7 . Full Offload SMF N4 PFCP VM/container #m UPF-C DPDK Hypervisor UPF x86 Server PCIe N3 GTP UPF-U IP N6 Access Data Network PM counters Network 25G/40G/100G 25G/40G/100G SmartNIC 7 

8 . FPGA SmartNIC Accelerates UPF Features S-GW/UPF P-GW/UPF GW ACL Filters UPF-U features offloaded by SmartNIC H-QoS Lawful ➢ Packet routing forwarding HandOver I/F DPI Profile Mgmt Interception ➢ GTP termination (if needed) UPF-C ➢ Gating, redirection & traffic steering X86 ➢ QoS Server PCIe ➢ Packet buffering Access FPGA Network ➢ Packet duplication UPF-U ➢ ACL GTP IP SmartNIC ➢ Lawful interception ➢ PM counters collection for billing ➢ IPsec encryption & decryption (for N3IWF) SmartNIC Forwarding Engine 8 

9 . I/F Between UPF-C and UPF-U SMF N4 PFCP VM/container #m UPF-C DPDK Hypervisor ? UPF x86 Server PCIe N3 GTP UPF-U IP N6 Access Data Network PM Counters Network 25G/40G/100G 25G/40G/100G SmartNIC 9 

10 .Options for UPF-C to UPF-U I/F • Control Plane Messages • Send in-band control packets between UPF-C and UPF-U • Option 1: dedicated control packets for this purpose, new standard • Option 2: use an existing SDN I/F (for example, OpenFlow, P4 & P4 run-time) • Use DPDK HW offload APIs • Use existing DPDK methods for HW offload 10 

11 . Control Plane Messages In-band SMF Approach N4 PFCP VM/container #m UPF-C DPDK Hypervisor UPF x86 Server PCIe N3 GTP UPF-U IP N6 Access Data Network PM Counters Network 25G/40G/100G 25G/40G/100G SmartNIC 11 

12 . Dedicated Control Plane Messages • Benefit: good performance • Control packets consume a small portion of the large data plane packets • Dedicated Control Plane Messages • Need to define a spec for control plane message content for all UPF-U features • Need to implement a specific design in both UPF-C and UPF-U • Need to update the spec and implementation for new UPF-U features • Need to address error reporting and retransmission • Existing SDN I/F • Need to adapt existing I/F to cover all UPF features not easily covered by existing SDN protocols • For example: cover policies, billing reports, etc. 12 

13 . Using DPDK HW Offload APIs Suggested SMF Approach N4 PFCP VM/container #m UPF-C DPDK flow APIs rte_flow DPDK Hypervisor UPF x86 Server PCIe N3 GTP UPF-U IP N6 Access Data Network PM Counters Network 25G/40G/100G 25G/40G/100G SmartNIC 13 

14 . DPDK-Based APIs for UPF-C to UPF-U • Most UPF applications are already implemented in DPDK • For example, 5G UPF based on VPP: https://github.com/travelping/vpp • rte_flow is the natural choice for DPDK applications • UPF is flow based, maps nicely to DPDK rte_flow offload APIs (generic flow API) • Avoids vendor lock-in • Supported by a large variety of vendors • Becoming a de-facto standard • Futureproof: maintained and enhanced by the DPDK community • Provides methods for handling flow validation • Flexible enough to cover almost all UPF-U features 14 

15 . SUGGESTED DPDK rte_flow IMPROVEMENTS REQUIRED FOR UPF OFFLOAD 

16 .Improve DPDK rte_flow APIs Performance • UPF requires a large number of flows (e.g., 1M flows) • Need to improve the rte_flow configuration rate • Add burst write configurations • Batching of rte_flow entries and then committing the batch to the HW offload • Use shared memory and DMA for flow data structures • Provide pointers to complete rte_flow data structures • This is required for delivering PM counters for a large number of rte_flows • Create a single rte_flow template, then populate just a few variable fields • Avoids configuration of repeated fields in the same rte_flow template 16 

17 . GTP Header • GTP header match is already supported in rte_flow • Need to add GTP-U encap/decap • GTP-U header encapsulation and decapsulation rte_flow actions • Very similar to other tunnel headers that are already supported: VxLAN, NVGRE, MPLS and raw_encap/decap • Should include optional support for 5GS GTP-U extension header ➢ The GTP-U Extension Header for 5GS is called "PDU Session Container" 17 

18 .GTP-U Extension Header for 5GS 18 

19 . Summary • UPF is the 5G element implementing user plane data path • UPF can be placed at the edge • There is a need for UPF HW offload • UPF can be split into UPF-C and UPF-U • Need to define an I/F between UPF-C and UPF-U • DPDK rte_flow APIs are a good option for implementing this I/F • Need to implement some enhancements in rte_flow for optimal support of UPF 19 

20 . x Thank You BARAK PERLMAN, CTO BRIAN KLAFF, MARKETING DIRECTOR BARAK@ETHERNITYNET.COM BRIANK@ETHERNITYNET.COM