STRUCTURE AND DESIGN OF SOFTWARE-DEFINED NETWORKS TEEMU KOPONEN NICIRA, VMWARE

Transcription

1 STRUCTURE AND DESIGN OF SOFTWARE-DEFINED NETWORKS TEEMU KOPONEN NICIRA, VMWARE

2 WARNING: I DON T DESIGN PROTOCOLS. I WRITE C++. TRANSLATION: THIS IS NOT YOUR TYPICAL NETWORK TALK.

3 AGENDA: 5 YEARS OF SDN 1. FALLACIES AND PROMISE OF SDN. 2. QUEST FOR STRUCTURES & ABSTRACTIONS IN NETWORKING. 3. PRACTICAL, EMERGING ABSTRACTIONS: FABRIC AND NETWORK VIRTUALIZATION. 4. POTENTIAL IMPLICATIONS FOR NETWORKING.

4 FALLACIES OF SDN

5 TRADITIONAL VIEW OF SDN OPENFLOW OPENFLOW OPENFLOW

6 ANYTHING WRONG?

7 CENTRALIZATION AVAILABILITY AND SCALING CALL FOR DISTRIBUTION.

8 FINE-GRAINED CONTROL OPENFLOW FIRST PKT OPENFLOW FIRST PKT OPENFLOW FIRST PKT LOW-LEVEL FLOW MANAGEMENT IS HARD IN LARGE-SCALE.

9 UNIFIED HARDWARE PIPELINE BROADCOM MARVEL FULCRUM VENDORS PREFER DIFFERENTIATION AND DIE SURFACE MATTERS.

10 FAILURE DOMAINS THERE WILL BE NETWORK PARTITIONS.

11 DID I LOSE MY FAITH IN SDN?

12 NO, EXACTLY THE OPPOSITE!

13 DISTRIBUTION IS A GOOD SERVANT BUT A BAD MASTER DATA PLANE: SPREADING STATE ACROSS THE NETWORK COMPLICATES THE DESIGN. CONTROL PLANE IS THE WORST EXAMPLE: DISTRIBUTED ALGORITHMS ARE COMPLEX. ONLY INDIRECT MEANS FOR CONTROL.

14 FREEING OURSELVES FROM TOPOLOGY PHYSICAL TOPOLOGY SHOULD NOT DRIVE THE CONTROL DESIGN. DECOUPLING CONTROL FROM TOPOLOGY: ALLOWS FOR SIMPLER OVERALL DESIGN. ALLOWS FOR DISTRIBUTED SYSTEMS PRINCIPLES. ALLOWS FOR RECONSIDERING THE NETWORK DESIGN.

15 QUEST FOR STRUCTURES & ABSTRACTIONS IN NETWORKING

16 WHERE ARE WE TODAY?

17 HOW DID WE GET HERE? A GUARANTEED RECIPE FOR DISASTER: 1. INVENT A NEW DATA PLANE MECHANISM. 2. HACK A NEW CONTROL PLANE FOR IT. 3. JUMP BACK TO 1. PHYSICAL TOPOLOGY DROVE THE CONTROL DESIGN!

18 THE MISSING PRINCIPLES OF MODULARITY SEPARATION OF CONCERNS CONTAIN A PROBLEM. CONTAIN ITS SOLUTION. MODULES GET DECOUPLED. HIDING COMPLEXITY ABSTRACTIONS HIDE DETAILS FROM THE REST. HARMFUL DEPENDENCIES DON T CREEP IN. BUT...

19 DID SOMEONE SAY IT WOULD BE EASY? NO FIRM STRUCTURES FOR THE CONTROL PLANE AFTER PAST 30 YEARS OF NETWORKING. ABSTRACTIONS AND STRUCTURES ARE TRIVIAL TO MISS. YOU HAVE TO PRACTICALLY STUMBLE INTO THEM. EXACTLY THAT HAPPENED TO US. FOLLOWING IS NOT ABOUT PAPER DESIGNS!

20 STRUCTURE I : FABRIC

21 MPLS: ARGUMENT FOR EDGE/CORE SPLIT ROUTING ROUTER SIMPLE FORWARDING MPLS EDGE NEIGHBOR DOMAIN ROUTING ROUTER MPLS EDGE DOMAIN INTERNAL NEIGHBOR DOMAIN

22 HYPERVISORS ARE THE NEW EDGE SIMPLE FORWARDING HOST HOST HYPERVISOR HYPERVISOR VM VM DOMAIN INTERNAL

23 BENEFITS: SEPARATION OF CONCERNS EDGE IMPLEMENTS THE NETWORK POLICY. CORRECTNESS & FLEXIBILITY OF FUNCTION ESSENTIAL. SPEED LESS. FABRIC MOVES THE PACKET ACROSS THE NETWORK. SIMPLICITY OF FUNCTION. RELIABILITY AND CAPACITY CRITICAL. EDGE AND FABRIC CAN EVOLVE INDEPENDENTLY WITH DIFFERENT GOALS!

24 CLEAR DIVIDE BETWEEN HW & SW EDGE CORRECTNESS & FLEXIBILITY OF FUNCTION ESSENTIAL. SPEED LESS SO. FABRIC RELIABILITY AND CAPACITY CRITICAL. SIMPLE & STABLE FUNC. X86 SIMPLE ASICS

25 TRUCTURE 2 : NETWORK VIRTUALIZATION

26 HIDING COMPLEXITY TODAY CONFIGURING A POLICY SPANS ALL ELEMENTS. SIMPLE POLICY: A CAN T TALK TO B. WHY SHOULD ADMIN CONSIDER ANY DETAILS BETWEEN? A B A VIRTUAL B

27 NETWORK VIRTUALIZATION VIRTUAL VIRTUAL ROUTER VIRTUAL PHYSICAL

28 GENERALIZATION: NESTED VIRTUALIZATION TIER 1 CONTROLLER VIRTUAL TIER 2 VIRTUAL CONTROLLER VIRTUAL CONTROLLER TIER 3 VIRTUAL CONTROLLER VIRTUAL CONTROLLER TIER 4 VIRTUAL CONTROLLER VIRTUAL CONTROLLER

29 IDENTIFYING THE SCOPE OF VIRTUAL LOCALITY OF CONNECTIVITY VIRTUAL SPANS AN AREA OF GOOD CONNECTIVITY. FAILURE DOMAINS VIRTUAL CORRESPONDS TO A SINGLE FAILURE DOMAIN SEPARATION OF POLICIES VIRTUAL INTERFACE HIDES LOWER LEVEL POLICIES FROM ABOVE.

30 FABRIC + VIRTUALIZATION VIRTUAL VIRTUAL ROUTER VIRTUAL PHYSICAL EDGE FABRIC EDGE

31 VIRTUAL ES, ROUTERS, SERVICES... VIRTUAL SERVICE VIRTUAL ROUTERS VIRTUAL VIRTUAL PHYSICAL EDGE FABRIC EDGE

32 STRUCTURES SUMMARY FABRIC HARDWARE TO DELIVER PACKETS ACROSS NETWORK. SOFTWARE EDGE IMPLEMENTS THE SEMANTIC INTELLIGENCE. VIRTUALIZATION VIRTUAL TOPOLOGIES SHIELD USER FROM LOW- LEVEL DETAILS. ADMIN FOCUSES ON POLICIES. IMPLEMENTED AT THE EDGE.

33 CONJECTURE: SOFTWARE WILL TAKE OVER

34 LONG TIME AGO... SOFTWARE CONTROL PLANE SOFTWARE DATA PLANE

35 MORE RECENTLY... SOFTWARE CONTROL PLANE HARDWARE DATA PLANE

36 TODAY IN VIRTUALIZED ENVIRONMENTS SOFTWARE CONTROL PLANE EDGE HARDWARE FABRIC DATA PLANE DATA SOFTWARE PLANE

37 CLEAR DIVIDE OF ROLES HARDWARE FABRIC SOFTWARE EDGE HIGH AGGREGATE BANDWIDTH, RELIABILITY HIGHLY FLEXIBLE PROVIDER FOR NETWORK SEMANTICS A MODERN VERSION OF END-TO-END PRINCIPLE!

38 SOFTWARE FORWARDING NEVER WORKS... THIS TIME IT S DIFFERENT: HARDWARE REMAINS RESPONSIBLE FOR AGGREGATE BANDWIDTH. SIMILARLY, HIGH FAN-OUT. SOFTWARE FORWARDING IS A TAX FOR SERVERS. USING A FEW PERCENT OF CPUS NOT REALLY AN ISSUE.

39 CHANGE OF DESIGN PRIORITIES STRICT HW LIMITATIONS (MINIMIZE DIE SURFACE) SIMPLE CONTROL PLANE DESIGN CONTROL PLANE DESIGN ADAPTS SOFTWARE FORWARDING ADAPTS (FLEXIBLE MATCHING AND OPERATIONS) SYSTEM COMPLEXITY SIMPLER SYSTEM

40 NETWORKS AS SYSTEMS

41 CLASSIC LAYERED CONTROL PLANES WAN BGP REGIONS MPLS CARRIER ETHERNET SITES IS-IS OSPF SUBNETS ETHERNET STP TRILL

42 LAYERED CONTROL PLANES IN SDN WAN GLOBAL VIRTUAL CONTROLLER REGIONS VIRTUAL CONTROLLER VIRTUAL CONTROLLER SITES VIRTUAL CONTROLLER VIRTUAL CONTROLLER SUBNETS VIRTUAL CONTROLLER VIRTUAL CONTROLLER

43 FORGET THE PROTOCOLS

44 EMPEROR S NEW CLOTHES HACKING WITH NOX REQUIRES NO KNOWLEDGE ABOUT PROTOCOLS. NETWORK CONTROL AT ANY SCALE IS NO DIFFERENT: ANY DISTRIBUTED SYSTEMS DEVELOPER CAN ARRIVE WITH A DESIGN! REMEMBER FAILURE DOMAINS, LOCALITY AND SEPARATION OF POLICIES... WHAT SPECIAL IS LEFT IN NETWORKING AFTER THIS? WE CAN REASON ABOUT NETWORKS AS PLAIN, STANDARD SYSTEMS, NOT AS A COLLECTION OF DISTRIBUTED PROTOCOLS!

45 TAKEAWAYS

46 SUMMARY SDN IS AN OPPORTUNITY TO REVISIT THE NETWORK DESIGN. FABRIC & NETWORK VIRTUALIZATION GOOD EXAMPLES. CLASSIC ASSUMPTIONS ARE QUICKLY CHANGING: SOFTWARE FORWARDING TAKES OVER HARDWARE AS THE PROVIDER OF NETWORK SEMANTICS. DISTRIBUTED SYSTEMS REPLACE THE BAG OF CONTROL PROTOCOLS. THIS IS EXACTLY WHAT SOFTWARE IN SDN MEANS!

47 QUESTIONS?