Duet: Cloud Scale Load Balancing with Hardware PDF
Preview Duet: Cloud Scale Load Balancing with Hardware
Duet: Cloud Scale Load Balancing with Hardware and Software Rohan Gandhi Hongqiang Harry Liu Guohan Lu J i t u P a d h ye Y. Charlie Hu Lihua Yuan Ming Zhang 1 Load Balancer is Critical For Online Services Terminology Internet VIP – Virtual IP DIP – Direct IP Mux – Multiplexer VIP1, VIP2 Datacenter Store VIP-DIP mapping Load balancer (Mux) Split VIP traffic to DIPs Server Server Server Server . . . . . . DIP = 10.0.1.1 DIP = 10.0.2.2 DIP = 10.0.3.3 DIP = 10.0.4.4 bing.com OneDrive VIP1 = 1.1.1.1 VIP2 = 1.1.1.2 Load balancer provides high availability and scalability 2 Existing LBs Have Limitations Specialized Hardware LBs Too costly Poor robustness $100+ million for 15 Tbps 1+1 redundancy Software LBs Scale with demand High robustness Scale up/down according to n+1 redundancy VIP traffic Software LBs have cost and performance limitations 3 Software LB Design DC Network DIP2 Client SMux DIP1 VIP1 DIP1, DIP2 VIP1 . . . . Software LB Benefits: • High robustness • Scale with demand 4 Ananta: Cloud-scale load balancing [SIGCOMM’13] Software LB has Limitations 100 n 10 n o 80 o i t i alf )c taz 60 n e i i y sm 1 litU 40 c n ( U e t P 20 a C L 0.1 0 100k 300k 450k 100k 300k 450k Traffic (pkts/sec) Traffic (pkts/sec) High latency inflation: 200 usec Low capacity: 300k pkts/sec 5k SMuxes needed at 15Tbps traffic in 50k server DC 5 How can we build high performance, low cost and robust load balancer? Duet ideas • Use commodity switches as hardware Muxes • Use software Muxes as a backstop 6 Can Switch Act As a Mux Switches offer: • High capacity (500+ million pkts/sec) • Low latency inflation (1 usec) Mux functionalities Switch resources • Split VIP traffic across DIPs • ECMP • Forward VIP traffic to DIPs • Tunneling 7 Implementing HMux on Switch VIP DIPs Forwarding Table ECMP Table Tunneling Table 10.0.0.1 Index DIPs VIP 1.1.1.1/32 10.0.0.2 1.1.1.1/32 0 10.0.0.1 20.0.0.1 1.1.1.2/32 1 10.0.0.2 1.1.1.2/32 20.0.0.2 2 20.0.0.1 3 20.0.0.2 HMux Dest: Src: Dest: Src: Dest: Src: VIP Client DIP HMux VIP Client 8 Key Design Challenges • Limited switch memory • High failure robustness • VIP assignment • VIP migration 9 Challenge 1: Switches have Limited Memory Workload: 100k+ VIPs and 1+ millions DIPs Single HMux cannot store all VIPs and DIPs Forwarding Table ECMP Table Tunneling Table Index DIPs VIP 1.1.1.1/32 0 10.0.0.1 1.1.1.2/32 1 10.0.0.2 2 20.0.0.1 3 20.0.0.2 Limits #VIPs Limits #DIPs Table Forwarding ECMP Tunneling Max. size 16k 4k 512 Max VIPs Max DIPs 10
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