Sharing Cloud Networks Lucian Popa, Gautam Kumar, Mosharaf Chowdhury Arvind Krishnamurthy, Sylvia...
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Transcript of Sharing Cloud Networks Lucian Popa, Gautam Kumar, Mosharaf Chowdhury Arvind Krishnamurthy, Sylvia...
Sharing Cloud Networks
Lucian Popa, Gautam Kumar, Mosharaf ChowdhuryArvind Krishnamurthy, Sylvia Ratnasamy, Ion Stoica
UC Berkeley
State of the Cloud
Network???
2
Guess the Share
3
B2
A1
B1
A2
A3
Link L
Alice : Bob = ? : ?
3 : 1 1 : 1 2 : 1 3 : 2TCP Per flow Per Source Per Destination
Per-VMProportional
ChallengesNetwork share of a virtual machine (VM) V depends on
»Collocated VMs,»Placement of destination VMs, and »Cross-traffic on each link used by V
Network differs from CPU or RAM»Distributed resource»Usage attribution (source, destination, or both?)
Traditional link sharing concepts needs rethinking
4
Requirements
5
High Utilization
Min Bandwidth Guarantee
Aggregate Proportionali
ty
Network shares
proportional to the
number of VMs
Introduce performan
ce predictabili
ty
Do not leave bandwidth unused if there is demand
Requirement 1:Guaranteed Minimum B/WProvides a minimum b/w guarantee for each VM
Captures the desire of tenants to get performance isolation for their applications
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A B X
BminA
BminB
BminX
…
All VMs
Requirement 2:Aggregate ProportionalityShares network resources across tenants in proportion to the number of their VMs
Captures payment-proportionality»Similar to other resources like CPU, RAM etc.
Desirable properties»Strategy-proofness: Allocations cannot be
gamed»Symmetry: Reversing directions of flows does
not change allocation
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Design Space
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High Utilization
Min Bandwidth Guarantee
Aggregate Proportionali
ty
Strategy-Proofness
Symmetry
Requirement 3:High Utilization
Provides incentives such that throughput is only constrained by the network capacity
»Not by the inefficiency of the allocation or by disincentivizing users to send traffic
Desirable properties»Work Conservation: Full utilization of
bottleneck links» Independence: Independent allocation of one
VM’s traffic across independent paths
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Tradeoff 1
Design Space
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High Utilization
Min Bandwidth Guarantee
Aggregate Proportionali
ty
Work Conservatio
n
Strategy-Proofness
Independence
Symmetry
Tradeoff 1: Min B/W vs. Proportionality
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Share of Tenant A can decrease arbitrarily!
B2 A1 B1
A2
Link L with Capacity C
C/2
C/2
B3
C/3
2C/3
Tradeoff 1 Tradeoff 2
Design Space
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High Utilization
Min Bandwidth Guarantee
Aggregate Proportionali
ty
Work Conservatio
n
Strategy-Proofness
Independence
Symmetry
Tradeoff 2:Proportionality vs. Utilization
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A1
A3
B1
B3
A2
A4
B2
B4
Link Lwith
Capacity C
C/4
C/4
C/4
C/4
To maintain proportionality, equal amount of traffic must be moved from A1-A2 to A1-A3 =>
Underutilization of A1-A3
Per-link Proportionality
Restrict to congested links only
Share of a tenant on a congested link is proportional to the number of its VMs sending traffic on that link
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Per Endpoint Sharing (PES)
Five identical VMs (with unit weights) sharing a Link L
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B2
A1
B1
A2
A3
Link L
Per Endpoint Sharing (PES)
Resulting weights of the three flows:
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Link L
3/23/22
To generalize, weight of a flow A-B on link L is . .
NA = 2
B2
A1
B1
A2
A3
Per Endpoint Sharing (PES)
Symmetric
Proportional»sum of weights of flows of a tenant on a link L =
sum of weights of its VMs communicating on that link
Work Conserving
Independent
Strategy-proof on congested links17
WAWA-B = NA NB
WB+ = WB-A
Generalized PES
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A B
α > β if L is more important to A than to B (e.g., A’s access link)
W
AWA-B = WB-
A= α NAN
B
WB+ β
L
Scale weight of A by α Scale weight of B
by β
One-Sided PES (OSPES)
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A B
α = 1, β = 0 if A is closer to L
α = 0, β = 1 if B is closer to L
W
AWA-B = WB-
A= α NAN
B
WB+ β
L
Scale weight of A by α Scale weight of B
by β
Per Source closer to sourcePer Destination closer to
destination
Highest B/W Guarantee
*In the Hose Model
Comparison
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Per Flow
Per Sourc
e
Static Reservatio
n
Link PES
OSPES
Link Proportionality Symmetry ✓ ✗ ✓ ✓ ✓
Strategy-Proofness
✗ ✓ ✓ ✓ ✓
Utilization Independence ✓ ✓ ✓ ✓ ✓
Work Conservation
✓ ✓ ✗ ✓ ✓
B/W Guarantee
Full-bisection B/W Network
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Tenant 1 has one-to-one communication pattern
Tenant 2 has all-to-all communication pattern
OSPES
MapReduce Workload
22W1:W2:W3:W4:W5 = 1:2:3:4:5
OSPES
Summary
Sharing cloud networks is all about making tradeoffs
»Min b/w guarantee VS Proportionality»Proportionality VS Utilization
Desired solution is not obvious»Depends on several conflicting requirements and
properties » Influenced by the end goal
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