Introduction to SDN
Daniel Farrell
SDN Intern, Red Hat
VERY QUICK: INTRO TO ME
Daniel Farrell, SDN Intern Red Hat
Very Quick: Intro to ME
Code!
- Worked on OpenFlow, OpenStack and OpenDaylight
VERY QUICK: INTRO TO ME
Robots!
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(Craft) Beer!
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Biking!
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SCUBA!
rationale over Design
RATIONALE OVER DESIGN
SDN is a concept, not a piece of software
Very Recent Development
Game: When was X started?
TCP?
TCP?
1973
Python?
PYTHON?
1989
SDN?
SDN?
~2008-2010*
*Hard to put a date on a conceptual change
Very Rapid ACCEPTANCE
Huge industry shift already
lol @ IPv6
VERY RAPID ACCEPTANCE
Google's G-Scale Network
VERY RAPID ACCEPTANCE
*Many* other deployments in the works
Not socrates, But...
Going to ask and answer my own questions
How do we build Software?
HOW DO WE BUILD SOFTWARE?
Divide the problem into tasks
HOW DO WE BUILD SOFTWARE?
Build abstractions for the tasks
HOW DO WE BUILD SOFTWARE?
Modular interface between abstractions
HOW DO WE BUILD SOFTWARE?
Allows code reuse
HOW DO WE BUILD SOFTWARE?
Can change implementations if you respect interfaces
HOW DO WE BUILD SOFTWARE?
Separates concerns
HOW DO WE BUILD SOFTWARE?
So fundamentally, it's all about abstractions
What Abstractions Have been Applied to NETWORKING?
Data vs Control Plane
Data Plane
DATA PLANE
- Look at packet header
- Look at forwarding state
-
Make forwarding decision
Control Plane
CONTROL PLANE
Puts the forwarding state in boxes
Data Plane Abstractions
DATA PLANE ABSTRACTIONS
Great abstractions, allowed the Internet to develop
DATA PLANE ABSTRACTIONS
DATA PLANE ABSTRACTIONS
Modular layers with well-defined API
DATA PLANE ABSTRACTIONS
Allows for innovation at each layer
(Ethernet -> Fiber)
(TCP [Reno, Vegas, New Reno, BIC, CUBIC])
Control PLANE ABSTRACTIONS?
CONTROL PLANE ABSTRACTIONS
None
CONTROL PLANE ABSTRACTIONS
Routing and isolation?
CONTROL PLANE ABSTRACTIONS
Routing and isolation?
Mechanisms, not abstractions
CONTROL PLANE ABSTRACTIONS
Routing and isolation?
No modularity, no reuse
Let's Design Some Abstractions
WHAT PROBLEM IS CP SOLVING?
WHAT Problem IS CP SOLVING?
Compute forwarding state
WHAT PROBLEM IS CP SOLVING?
Three constraints:
- Possible on low-level hardware/software
- Accounts for full network topo
- Able to configure every box
CP Abstractions
CP ABSTRACTIONS
Issue: Possible on low-level hardware/software
Abstraction: General forwarding model
CP ABSTRACTIONS
Issue: Accounts for full network topo
Abstraction: Global network abstraction
CP ABSTRACTIONS
Issue: Able to configure every box
Abstraction: Abstract network view
General forwarding model
GENERAL FORWARDING MODEL
Need to not care about Cisco vs Juniper vs Extreme...
GENERAL FORWARDING MODEL
Express intent about what happens to packets
GENERAL FORWARDING MODEL
OpenFlow 1.0/1.3, BGP
Global network abstraction
GLOBAL NETWORK ABSTRACTION
Need to hide complex distributed algos
GLOBAL NETWORK ABSTRACTION
Network Operating System
GLOBAL NETWORK ABSTRACTION
Network Operating System
Runs on commodity servers
GLOBAL NETWORK ABSTRACTION
Info from boxes provides view
GLOBAL NETWORK ABSTRACTION
Config to boxes controls forwarding
GLOBAL NETWORK ABSTRACTION
Abstract network view
ABSTRACT NETWORK VIEW
We have a global view, but it's still complex
ABSTRACT NETWORK VIEW
ABSTRACT NETWORK VIEW
Control program shouldn't need to think about that
ABSTRACT NETWORK VIEW
Provide virtualized (abstract) view
ABSTRACT NETWORK VIEW
Analogy: Programming using compilers
ABSTRACT NETWORK VIEW
Do you write in x86 assembly?
ABSTRACT NETWORK VIEW
Write in high level language, use compiler
ABSTRACT NETWORK VIEW
Compiler is complex, but reusable
ABSTRACT NETWORK VIEW
Abstraction win!
ABSTRACTION WIN!
Control program: User goals -> abstract view
ABSTRACTION WIN!
Virtualization layer: Abstract -> global network
(compiler)
ABSTRACTION WIN!
Network OS: Global view -> actual boxes
ABSTRACTION WIN!
Info travels in both directions
s/->/<->
Magic?
MAGIC?
Where did the complexity go?
MAGIC?
We didn't eliminate it!
MAGIC?
We moved it to the right places
MAGIC?
Virtualization and Network OS are complex!
MAGIC?
But they are reusable!
(Think: compilers, modules with APIs)
Implementation Details
OpenFlow
OPENFLOW
*Very* simple protocol
OPENFLOW
Defines forwarding state
OpenFlow
Vendor agnostic
OPENFLOW
Match condition and action
OPENFLOW
If a packet matches these conditions...
(MAC, IP, VLAN, port, etc.)
OPENFLOW
...take these actions
(drop, rewrite, forward, etc.)
OpenDaylight
OPENDAYLIGHT
Open Source SDN controller
OPENDAYLIGHT
OPENDAYLIGHT
Contact
Daniel Farrell
SDN Intern, Red Hat
Let's have a beer/coffee and talk about SDN/ODL/Linux/etc!
919.576.0112