demystifying sdn saurav das [email protected] at&t talk 3/27/14 1
TRANSCRIPT
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A number of slides are courtesy of
www.sdnacademy.com
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Outline
• What is SDN? (or how was it originally intended)
• Different Shades of SDN
• SDN Myths and Misconceptions
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(A) Forwarding Abstraction: Match-Action Tables
(B) State-Distribution Abstraction: Global View
Network OS running on distributed controllers
NORTHBOUND
SOUTHBOUND
Configuration; Control over Forwarding; Monitoring
What is SDN?
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What is an Abstraction?
Data – plane abstractions
Where are the control-plane abstractions?
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Where are the Control-Plane Abstractions? • Networking is about getting stuff from here to there …• Is OSPF a topology abstraction?• Is OSPF a routing abstraction?
• Can I use it to route IPv6 traffic? • well you need v2 for IPv4 and v3 for IPv6
• Can I use it to route multicast traffic?• no you need MOSPF or PIM
• Can I use it in Ethernet networks?• no you need TRILL (with IS-IS) for that
State Distribution Mechanisms
Switch Operating
System
DistributedNetwork Functions
IGP- Route Advert, Link-State
OSPFv2
TE Label Distribution
RSVP-TE
VPN-IPv4 Route Advert
MP-BGP
E-BGP learned Route Advert
I-BGP + RR
PE Label Distribution
LDP
Developing a Control Plane Abstraction
Requires
Developing a Data Plane (Forwarding) Abstraction
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Towards a Forwarding Abstraction
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(A) Forwarding Abstraction
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A way to define forwarding behavior that is not layer or vendor specific
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Interfaces are the Realizations of Abstractions
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(B) State Distribution Abstraction
Abstracted away by Network Operating System
State Collection Dissemination & Synchronization
Application Isolation
Proposed abstraction: global network view
Control program should not have to handle distributed-state details
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App
Switch
Switch
Switch
App App
SwitchSwitch
Controller
northbound interface
So What is SDN?
southboundInterface eg. OpenFlow
Forwarding Abstraction:Match-Action Tables
Control Abstraction:Global View
Interfaces are the Realizations of Abstractions
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What is SDN? – A Simpler View
SDN has two defining characteristics.
First, it physically separates the control plane (which
decides how to handle the traffic) from the data plane
(which forwards traffic according to decisions that the
control plane makes). Second, SDN consolidates the control plane, so that a single instance controls multiple data- plane elements
-- The Road To SDN, http://queue.acm.org/detail.cfm?id=2560327
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Benefits of SDN1.Simpler Control with Greater Flexibility• Networks work because we can master complexity, but what
we should be doing is extracting simplicity, with the right abstractions
2.Programmability: Speed of Innovation, Ease of Service Insertion & Faster Time to Market• Does not involve changing/creating a fully distributed
protocol
3.Lower Total Cost of Ownership (TCO)• Lower Opex – easier to manage, troubleshoot, emulate,
automate, optimize• Lower Capex – replacing proprietary hardware, pay for what
you need and no more.
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[1] ‘Pure’ SDN / ‘True’ SDN?
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(A) Forwarding Abstraction: Match-Action Tables
(B) State-Distribution Abstraction: Global View
Network OS running on distributed controllers
NORTHBOUND
SOUTHBOUND
Configuration; Control over Forwarding; Monitoring
Separation D <---> C
Simplicity
Programmability
Lower Capex
Lower Opex
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Different Shades of SDN
• ‘Pure’ SDN or ‘True’ SDN
• Orchestration/ Automation/ Gluework• Traditional Networking + SDN ‘Hook’• Overlay Networks for DC Network Virtualization• Traditional Networking + White-Box• Traditional Networking + White-Box + Orchestration• Decoupled Traditional Networking• Decoupled Traditional Networking + Global View• Open Source Networking
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[2] Orchestration/Automation/GlueworkSeparation
D <---> C
Simplicity
Programmability
Lower Capex
Lower Opex
“Controller”
VendorX
VendorY
VendorZ
CLI
EMS EMS
ProvidesAutomation
By Orchestrating Across
Automation ProgrammabilityModified NMS, OpenStack, cli-scripts automateConfiguration & provisioning
Changing Behavior
(if-then-else)
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[3] Traditional Networking + ‘SDN Hook’Legacy Preserving with Claimed Advantages A. Customer realizes benefits of SDN on same infrastructureB. Allows vendor to build SDN on existing products
CLI Replacement
‘Controller’ Instead of CLI expect scripts, write python programs
L2 L3 Tunnel ECMP ACL
PBR overide
Under traditional networking control
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[3] Traditional Networking + ‘SDN Hook’Legacy Preserving with Claimed Advantages A. Customer realizes benefits of SDN on same infrastructureB. Allows vendor to build SDN on existing products
PointSolutions PCE
Exampe:PCE based
PCEPBGP-LS
RSVP, LDPOSPF v2, OSPF v3, ISISMP-BGPI-BGP + RRMOSPF, PIM
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[3] Traditional Networking + ‘SDN Hook’Legacy Preserving with Claimed Advantages A. Customer realizes benefits of SDN on same infrastructureB. Allows vendor to build SDN on existing products
‘Controller’HybridSolutions /‘Ships-in-the-night’
Some VLANs have SDN control
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[3] Traditional Networking + ‘SDN Hook’Separation
D <---> C
Simplicity
Programmability
Lower Capex
Lower Opex
Legacy Preserving with Claimed Advantages A. Customer realizes benefits of SDN on same infrastructureB. Allows vendor to build SDN on existing products
CLI Replacement
‘Controller’ Instead of CLI expect scripts, write python programs
PointSolutions
‘Controller’ Eg. PCE based
HybridSolutions /‘Ships-in-the-night’
‘Controller’ Some VLANs have SDN control
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[4] Overlay Networking
‘Controller’
Separation D <---> C
Simplicity
Programmability
Lower Capex
Lower Opex
Underlying L2/L3 fabric
R1
R2 R3
B1
B2
B3
OrchestratorOpenStack,CloudStack,VMWare
vSwitch,vRouter
R1
R2
R3 B3
B1
B2
Context: Data center network virtualization for public/private cloud; presented from the viewpoint of the cloud provider (not the tenant)!
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[5] Traditional Networking + White Box
Data Path (Hardware)
Control Plane (Software)
Separation D <---> C
Simplicity
Programmability
Lower Capex
Lower Opex
Merchant Silicon
White -box
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[5.5] Traditional Networking + White Box + Orchestration
Data Path (Hardware)
Control Plane (Software)
Separation D <---> C
Simplicity
Programmability
Lower Capex
Lower Opex
Merchant Silicon
White -box
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[6] Decoupled Traditional NetworkingSeparation
D <---> C
Simplicity
Programmability
Lower Capex
Lower Opex
Traditional networking control plane
Usually proprietary, could be OF,See IETF ForCES
1. Software stacks
2. Merchant
Silicon
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[6.5] Decoupled Traditional Networking + Global View
Separation D <---> C
Simplicity
Programmability
Lower Capex
Lower Opex
Traditional networking control plane
Usually proprietary, could be OF,See IETF ForCES
1. Software stacks
2. Merchant
Silicon
‘Controller’
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[7] Open Source NetworkingSeparation
D <---> C
Simplicity
Programmability
Lower Capex
Lower Opex
Has Open Source ever worked in networking?What are the best know open source networking projects…• Quagga• OVS… not used in production without modification
What about controllers?:• No open source controller used in production• No open source networking project today is complete solution• Open source is part of the solution
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SeparateD <---> C
Simplicity
Programm-ability
Lower Capex
Lower Opex
True
SD
N
Orche
strati
on
/Aut
omati
onTr
aditi
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net
w. +
SDN ‘H
ook’
Trad
ition
al n
etw. +
Whi
te B
ox
Overla
y Net
works
for D
C ne
t virt
.
Decou
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Tr
aditi
onal
Net
w.Dec
oupl
ed Tr
ad.
n/w
+ Glo
bal V
iew
Open
Sour
ce
Different Shades of SDN
Trad
ition
al n
etw. +
Whi
te B
ox +
Orch.
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Myths & Misconceptions• SDN is Network Virtualization
• SDN == NFV
• SDN is about centralized control
• OpenFlow is not mature
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state behavior Interfacemsg
match Eth, VLAN, IP, L4flows1.0
Q4 ‘09
single message queuew/optional barriers
ports
forward {0, 1, n}
1.1Q1 ‘11
+ Multiple Tables/Pipelines:
+ Group Tables + forward 1-in-n (ECMP)+ match QinQ, MPLS, SCTP
+ match virtual ports
+ extensible match+ extensible actions
1.2Q4 ‘11
+ IPv6+ multiple controllers
1.3Q2 ‘12
+ per-flow metering+ tunnel-id
OpenFlow has evolved towards production readiness.
+ multiple channels (auxiliary connections)
1.4Q4 ‘13
+ optical ports+ synchronized tables
+ bundle messages
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Myths & Misconceptions• SDN is Network Virtualization
• SDN == NFV
• SDN is about centralized control
• OpenFlow is not mature
• OpenFlow does not work with current hardware
• OpenFlow does not scale
• Do we really need another protocol?
• I can’t just throw away my existing network …
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Source: Ed Crabbe, Google31
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Source: Ed Crabbe, Google32
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Source: Guru Parulkar
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34Source: Guru Parulkar
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Q & A