as well as the server Nikhil Handigol Stanford University Joint work with Nick McKeown and Ramesh Johari Datacenter Widearea Enterprise Cant choose path LOADBALANCER Client ID: 220563
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Slide1
Should a load-balancer choose the pathas well as the server?
Nikhil Handigol
Stanford University
Joint work with Nick
McKeown
and
Ramesh
JohariSlide2
Datacenter
Wide-area
EnterpriseSlide3
Can’t choose path :’(
LOAD-BALANCER
Client
ServersSlide4
Outline and goalsA new architecture for distributed load-balancing
joint (server, path) selection
Demonstrate a nation-wide prototype
Interesting preliminary resultsSlide5
I’m here to ask for your help!Slide6
Data Path (Hardware)
Control Path
OpenFlow
OpenFlow
Controller
OpenFlow Protocol (SSL)
Control PathSlide7
Custom Hardware
Custom Hardware
Custom Hardware
Custom Hardware
Custom Hardware
OS
OS
OS
OS
OS
Network OS
Feature
Feature
Software Defined Networking
Feature
Feature
Feature
Feature
Feature
Feature
Feature
Feature
Feature
Feature
7Slide8
Load Balancing is just Smart RoutingSlide9
Custom Hardware
Custom Hardware
Custom Hardware
Custom Hardware
Custom Hardware
Network OS
Load-balancing logic
Load-balancing as a network primitive
Load-balancing decision
Load-balancing decision
Load-balancing decision
Load-balancing decision
Load-balancing decision
9Slide10
Aster*
x
ControllerSlide11Slide12
http://
www.openflow.org
/videosSlide13
So far…
A new architecture for distributed load-balancing
joint (server, path) selection
Aster*
x
– a nation-wide prototypePromising results that joint (server, path) selection might have great benefits Slide14
What next?Slide15
How big is the pie?
Characterizing and quantifying the performance of joint (server, path) selectionSlide16
Load-balancing Controller
MININET-RTSlide17
Internet
Load-balancing ControllerSlide18
Clients
CDN
ISP
ModelSlide19
Parameters
Topology
Intra-AS topologies
BRITE (2000 topologies)
CAIDA (1000 topologies)
Rocketfuel
(~100
topos
.)
20-50 nodes
Uniform link capacitySlide20
Parameters
Servers
5-10 servers
Random placement
Service
Simple HTTP service
Serving 1 MB file
Additional server-side computationSlide21
Parameters
Clients
3-5 client locations
Random placement
Request pattern
Poisson process
Mean rate: 5-10
req
/secSlide22
Load-balancing strategies?Slide23
Simple but suboptimal
Complex but optimal
Design space
Disjoint-Shortest-Path
Joint
Disjoint-Traffic-EngineeringSlide24
Anatomy of a request-response
Client
Load-Balancer
Server
Response Time
Deliver
Retrieve
Choose
Request
Response 1
st
byte
Response last byte
Last byte
ackSlide25
Disjoint-Shortest-Path
CDN selects the least loaded server
Load = retrieve + deliver
ISP independently selects the shortest pathSlide26
Disjoint-Traffic-Engineering
CDN selects the least loaded server
Load = retrieve + deliver
ISP independently selects path to minimize max load
Max bandwidth headroomSlide27
Joint
Single controller jointly selects the best (server, path) pair
Total latency = retrieve + estimated deliverSlide28
Disjoint-Shortest-Path
vs
Joint
Disjoint-Shortest-Path
performs ~2x worse than
JointSlide29
Disjoint-Traffic-Engg. vs Joint
Disjoint-Traffic-Engineering
performs almost as well as
JointSlide30
Is Disjoint truly disjoint?
Client
Load-Balancer
Server
Response Time
Deliver
Retrieve
Choose
Request
Response 1
st
byte
Response last byte
Last byte
ack
Server response time contains network informationSlide31
The bottleneck effect
A single bottleneck resource along the path determines the performance.Slide32
Clients
CDN
ISP
The CDN-ISP gameSlide33
The CDN-ISP gameSystem load monotonically decreases
Both push system in the same directionSlide34
Summary of observations
Disjoint-SP is ~2x worse than Joint
Disjoint-TE performs almost as well as Joint
(despite decoupling of server selection and traffic engineering)
Game theoretic analysis supports the empirical observationSlide35
Questions for you!
How should I change the model to mimic a real CDN?Slide36
Questions for you!
How can I get real data?
What network topologies should I use?
How should I decide the no. of servers and their location?
How should I decide the client request pattern?Slide37
Questions for you!
How can I try it out in your network?
Elastic Load Balancing in EC2
Amazon
CloudFrontSlide38
Conclusion
A new architecture for distributed load-balancing
joint (server, path) selection
Aster*
x
- a nation-wide prototypeInteresting preliminary resultsFuture – Evaluation with real dataSlide39
Let’s chat more!Slide40
Extra slides…Slide41
Sample topologies
BRITE
CAIDASlide42
Disjoint-SP
vs
IdealSlide43
Disjoint-TE
vs
Ideal