Is Today's DC Architecture Adequate? Hierarchical network; 1+1 redundancy Equipment higher in the hierarchy handles more traffic more expensive, more efforts made at availability scale-up design Servers connect via 1 Gbps UTP to Top-of-Rack switches other links are mix of 1G, 10G; fiber, copper Uniform high capacity? Internet Internet Performance isolation? CR Data center typically via VLANS Layer 3 AR(AR CAR (AR Agility in terms of dynamically adding or shrinking servers? Layer 2 9LB Agility in terms of adapting to CR=L3 Core Router failures, and to traffic ·AR=L3 Access Router dynamics? S=L2 Switch Ease of management? 菌函因 LB= Load A= Top of Rack switch 21
Is Today’s DC Architecture Adequate? 21 Internet CR CR AR AR … AR AR LB S S LB Data Center Layer 3 Internet S S … S S … … Layer 2 Key: • CR = L3 Core Router • AR = L3 Access Router • S = L2 Switch • LB = Load Balancer • A = Top of Rack switch • Uniform high capacity? • Performance isolation? typically via VLANs • Agility in terms of dynamically adding or shrinking servers? • Agility in terms of adapting to failures, and to traffic dynamics? • Ease of management? • Hierarchical network; 1+1 redundancy • Equipment higher in the hierarchy handles more traffic • more expensive, more efforts made at availability ➔ scale-up design • Servers connect via 1 Gbps UTP to Top-of-Rack switches • Other links are mix of 1G, 10G; fiber, copper
Modern Data Center Network Architectures k Switch-centric servers use only 1 port for connection Interconnection and routing intelligence put into switches k Fat-Tree, PortLand, Vl2 k Server-centric Servers use multiple ports Participate in packet forwarding k dcell. ficonn bcube. mdcube cam Cube 2/8/2021 Tsinghua
Modern Data Center Network Architectures Switch-centric Servers use only 1 port for connection Interconnection and routing intelligence put into switches Fat-Tree, PortLand, VL2 Server-centric Servers use multiple ports Participate in packet forwarding DCell, FiConn, BCube, MDCube, CamCube 2/8/2021 Tsinghua 22 University
Outline Data center Introduction Data center network architectures Fat-Tree Vl2 dcell BCube FiOnn 2021/2/8 23
Outline Data Center Introduction Data Center Network Architectures Fat-Tree VL2 DCell BCube FiConn 2021/2/8 23
A Scalable, Commodity Data Center Network Architecture Main Goal: addressing the limitations of todays data center network architecture single point of failure Over-subscription of links higher up in the topology Key Design Considerations/Goals Allows host communication at line speed k no matter where they are located Backwards compatible with existing infrastructure no changes in application support of layer 2(Ethernet) k Cost effective k cheap infrastructure and low power consumption heat emission 24
A Scalable, Commodity Data Center Network Architecture Main Goal: addressing the limitations of today’s data center network architecture single point of failure Over-subscription of links higher up in the topology Key Design Considerations/Goals Allows host communication at line speed no matter where they are located! Backwards compatible with existing infrastructure no changes in application & support of layer 2 (Ethernet) Cost effective cheap infrastructure and low power consumption & heat emission 24
Fat-Tree Based dc architecture Inter-connect racks(of servers)using a fat-tree topology Fat-Tree: a special type of Clos Networks(after C Clos) K-ary fat tree: three-layer topology(edge, aggregation and core) each pod consists of (k/2 )2 servers &2 layers of k/2 k-port switches each edge switch connects to k/2 servers& k/2 aggr. switches each aggr. switch connects to k/2 edge& k/2 core switches k/2)2 core switches: each connects to k pods Fat-tree with K=2 Ed Pod o Pod 2 Pod 3
Fat-Tree Based DC Architecture Inter-connect racks (of servers) using a fat-tree topology Fat-Tree: a special type of Clos Networks (after C. Clos) K-ary fat tree: three-layer topology (edge, aggregation and core) each pod consists of (k/2)2 servers & 2 layers of k/2 k-port switches each edge switch connects to k/2 servers & k/2 aggr. switches each aggr. switch connects to k/2 edge & k/2 core switches (k/2)2 core switches: each connects to k pods Fat-tree with K=2 25