Transparent Edge Gateway for Mobile Networks

Transcription

1 Transparent Edge Gateway for Mobile Networks Ashkan Aghdai *, Mark Huang, David Dai, Yang Xu *, and Jonathan Chao * * NYU Tandon School of Engineering Huawei Technologies 1st P4 European Workshop (P4EU)

2 Mobile Edge Computing The Internet Cloud computing at the edge of the mobile network Proximity to users/devices Ultra-low latency High bandwidth Real-time access to radio network information Location awareness Apps Services Edge Cloud Apps Services Edge Cloud Mobile Network Apps Services Edge Cloud 2

3 Status Quo of content delivery in mobile networks User Mobile Network Internet LTE-Uu IP GTP-U Packet Data Network Gateway (PGW) Mobile networks use GPRS Tunneling Protocol to connect to the Internet 3

4 Status Quo of content delivery in mobile networks User Mobile Network Internet LTE-Uu IP GTP-U Not close enough to users High latency Pressure on core mobile network S/PGW MEC Service cluster Intermediate devices cannot terminate GTP tunnels; MEC services have 4 been deployed at PGW or IPX that connects PGW to the Internet

5 Our proposal: Transparent Traffic Steering at Mobile Networks User Mobile Network Internet LTE-Uu GTP-U Local cache instance P4 Switch as the Edge Gateway IP Intercept packets from the upstream pipe GTP-U Tunnels: L2 HDR OUTER IP HDR Transparent traffic steering: 1. No modifications to the existing components enodeb (Wireless IPbase station) Serving Gateway (SGW) Packet data network Gateway (PGW) User S/PGW Equipment (UE) Mobility Management Entity (MME) client and server 2. Do not terminate the GTP tunnels Programmable switches can seamlessly redirect the traffic to MEC UDP HDR GTP HDR INNER IP HDR PAY- LOAD 5

6 Challenging Issue: Interposing downstream MEC traffic into corresponding GTP tunnels User Mobile Network Internet LTE-Uu EGW: P4 Switch Interpose packets to the downstream pipe GTP-U Local cache instance IP S/PGW How to know the TEID for the downstream tunnel so that packets can be encapsulated into the proper GTP header? 6

7 Challenging Issue: Interposing downstream MEC traffic into corresponding GTP tunnels User Mobile Network Internet LTE-Uu EGW: P4 Switch GTP-U Local cache instance IP S1-AP Clone S1AP Processor S/PGW MME Program Extract downstream TEID from S1AP control messages during UE attach/handover 7

8 Design of EGW: Upstream Direction EGW GTP-U Service Context: Match on inner destination IP Miss Send to S/PGW S/PGW Hit Decapsulate inner IP packet Local Cache 8

9 Design of EGW: Upstream Direction Consistent load balancing When there are multiple instances in the MEC, EGW will perform load balance function to balance the load among instances. Load balancing is a wellstudied problem and a wide range of solutions are available for consistent translation of VIP to DIP Silkroad (Sigcomm 17) Faild/Beamer (NSDI 18) GTP-U Service Context: Match on inner destination IP Hit Decapsulate inner IP packet EGW IP VIP Miss Load balancer VIP DIP Send to S/PGW S/PGW DIP#1 DIP#2 DIP#N 9

10 Design of EGW: Downstream Direction Interpose packets from MEC to UE s GTP tunnel When a packet from MEC is received, the original IP header of the packet is copied to the inner IP header, while an outer IP header with enb and SGW IP addresses, an UDP header with GTP-U port designator, and a GTP-U header with UE s corresponding downstream TEID are added. 10

11 Summary: Basic functions of EGW Intercept packets from upstream GTP tunnel if they are destined to IP addresses within the MEC Send intercepted packets to MEC instances using load balancing Interpose packets from MEC to the proper downstream GTP tunnel Clone S1AP protocol message to an out-of-the-band S1AP processor 11

12 Implementation of EGW using P4 language 12

13 Verification on reference 5G protocol stack using OpenAirInterface (OAI) Server enb OAISIM UE Emulator HTTP Req HTTP Req Server w/ Netronome Smart NIC loaded w/ EGW P4 program A R P D I R S1AP Processor D I P 1 D I P 2 Results: Server HSS S/PGW MME 10G Physical Interface OAI Suite quickly becomes the bottleneck for byte packets: ~10mbps max throughput >100ms end-to-end latency Virtual Interface HTTP Server Redirect VIP 13

14 Pressure testing on Netronome P4 target Server Software Packet Generator Sending GTP packets with inner IP destination of VIP Server w/ Netronome Smart NIC loaded w/ EGW P4 program EGW works at 10G line rate w/ packets of size 150 Bytes and above D I P 1 D I P 2 14

15 Contributions and Summary Proposed EGW enables transparent traffic steering to/from mobile edge cloud on LTE and next generation 5G New applications of P4 language and programmable switches for Mobile networks Proof-of-concept using reference LTE protocol stack (Open AirInterface) and Netronome P4-compatible smart NIC 15

16 Thank You! 16