datacenter interconnection network design
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Datacenter Interconnection Network Design
Christina Delimitrou, Frank Nothaft, Milad Mohammadi, Laura Sharpless
May 26th 2011 – Final Project Presentation
Introduction
• Objective: Optimize for cost and power in data-center networks with competitive performance
• Evaluate alternative configurations in terms of Performance/Watt, Performance/$.
• Solution:
o Dragonfly topology o PAR routing o Virtual cut-through flow control
Dragonfly
• Fat Tree: Common interconnection network in large-scale datacenters
• Dragonfly: Cost effective use of resources Fewer hops (improves latency) Greater path diversity Fewer optical cables (improves cost)
Design Overview
1m
0.25m
0.25m
R R R R
R R R R
SHARED
SHARED
3m
9 racks = 1/2Group
1 Group = 18 racks
Routers per Group = 8
Design Overview
9 racks=1/2Group
1 Group
Cost Optimization: Connect neighboring groups with electrical wires
19 Columns
19
Co
lum
ns
Cost
• Free variables: number of groups, endpoints / router
• Routers / group, endpoints / router => number of groups
• Number of routers / group, endpoints / router determines optical
cables needed
PAR
• Implementation: o 4 VC's to avoid deadlock
VC0: Min routing in src group VC1: Val routing to intermediate VC2: Min routing to dest group VC3: Min routing within dest group
o Next: Threshold determination based on
simulation: 30 + (H x q)non-minimal > (H x q)minimal
Traffic Management
• Challenges: o Cloud abstraction o Simulate PAR misrouting
• Cloud abstraction:
o 1136 nodes = ~1% of total o Assumption: cloud node issues one packet per cycle
number of cloud nodes * ratio of cloud <-> real o Generation of packets leaving the cloud
Traffic Management
• Traffic Misrouting o Misrouting due to PAR varies inversely with offered traffic o Range is linear and fairly small (varies from 15-20%) o Currently, we say 20% of all packets are misrouted, and 1% of
packets sent between nodes in the cloud are misrouted to the outside world
• Hotspot Placement
o Randomly place hotspots in topology o Guarantee at least one non-cloud hotspot
Simulator Status
• Topology supports slicing • Router supports PAR • Traffic Manager Supports Hot Spot and Slicing • Partly implemented message routing
Next?
• Reevaluate PAR implementation • Complete Hot Spot implementation • Complete message routing implementation
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