experiences with programmable dataplanes · p4 language • p4: programming protocol-independent...

ExperienceswithProgrammableDataplanes

RonaldvanderPolSURFnet

TNC2016,12-16June,Prague(CZ)

Overview

•  MoLvaLonforProgrammableDataplanes•  OpenFlowandPipelines•  VariousNetworkSilicon•  TableTypePaQterns(TTPs)andP4•  Summary


Vertically integrated Closed, proprietary

Slow innovation Small industry

Specialized Operating System

Specialized Hardware

AppAppAppAppAppAppAppAppAppAppApp

Specialized Applications

Horizontal Open interfaces Rapid innovation

Huge industry

Microprocessor

Open Interface

Linux MacOS

Windows(OS) or or

Open Interface

(slidebyNick

(slidebyNickMcKeown,StanfordUniversity)

Vertically integrated Closed, proprietary

Slow innovation

AppAppAppAppAppAppAppAppAppAppApp

Horizontal Open interfaces Rapid innovation

ControlPlane

ControlPlane

ControlPlane or or

Open Interface

Specialized Control Plane

Specialized Hardware

Specialized Features

Merchant Switching Chips

Open Interface

(slidebyNickMcKeown,StanfordUniversity)

NetworkDisaggregaLon

•  BestofbreedinhardwareandsoXware•  OpenAPIs•  OpenHardware•  User/operatorincontrol

– Not(orless)dependentofvendorroadmaps–  Implementandexperimentwithnewprotocols

NetworkDisaggregaLonEcosystem


OpenFlow

•  OpenFlowgivesuser/operatordirectaccesstoflowforwardingtables

•  OpenFlowprovidesMatch/AcLonsemanLcs•  Supportedonmanyhardwareswitches

– PureOpenFlowswitches– Hybridswitches(convenLonalswitchadd-on)

•  Many(opensource)controllerpla]orms•  OpenFlowstartedthenetworkdisaggregaLonefforts


SoCASICbasedOpenFlowSwitches

•  ManybasedonBroadcomASICs(e.g.Trident)•  Onlyasmallfixedamountoflookuptables

– TCAM(wildcardentries,ACLs)– MACForwardingDatabase– L3longestprefixmatchtable– L3hostroutes


OpenFlow1.3MulLpleTables

•  Preventflowentryexplosion•  MulL-tablepipeline

table0

table1

tablen

ExecuteAction

Set

packet in packet outIngressPort

ActionSet = {}

ActionSet

Packet +IngressPort +

metadata Packet

ActionSet


MappingofFlowTables

ExecuteAction

Set

packet in packet outIngress

Port

ActionSet = {}

ActionSet

Packet +IngressPort +

metadata Packet

ActionSet

ingressport

packet in IPtable

MACtable

ExecuteAction

Set

egressport

packet out

OpenFlow 1.3 Pipeline

Broadcom Pipeline (simplified)

table0

ingressTCAM

based on Pica8 documentation

table1

tablen


BroadcomTridentII

•  ThereisveryliQlepublictechnicalinformaLonbecauseofBroadcom’sNDA

•  SeveralTCAMs,L2,L3,LPMtables•  UnifiedForwardingTable(UFT)memorybankscanbeallocatedto:– L2entries– ARPentries– L3LPMentries– ExactmatchACLentries


BroadcomTridentIIUFTBANK SIZE

0 4Kx420bits

1 4Kx420bits

2 16Kx420bits

3 16Kx420bits

4 16Kx420bits

5 16Kx420bits

6 1Kx420bits

7 1Kx420bits

8 1Kx420bits

9 1Kx420bits


}DedicatedL2MAC(32Kx105bits)

}

SharedEntries(256Kx105bits)

}

DedicatedL3hostentries(16Kx105bits)

TridentIIUFTCombinaLonsMode L2 L3hosts LPM

0 288K 16K 0

1 224K 56K 0

2 160K 88K 0

3 96K 120K 0

4 32K 16K 128K(77K–IPv6)


LimitaLonsofSoCASICs

•  FixedsemanLcstables(L2,L3,LPM,TCAM)•  Fixedsizetables(orlimitedresizing)•  NorecirculaLonofpackets(onepassthroughpipeline)


ASIC/OpenFlowLimitaLonExamples

•  LimitaLonofSoCASICs– OpenDaylightServiceFuncLonChaining(SFC)projectconfiguresmulLpletables

–  Theseendupin1TCAManddoesnotwork–  Result:genericapplicaLonslikeODLSFCcannotbeused;applicaLonneedstobeadaptedtoASIC

•  LimitaLonofOpenFlow–  SLlldependenceonSDOsandvendorsfornewencapsulaLons/protocols

– WewanttoexperimentwithNetworkServicesHeader(NSH),butnosupportinOpenFlow


ProgrammableNetworkSilicon•  FPGAs(FieldProgrammableGateArrays)+TCAM+DDR

–  CorsaDP6410*)•  NetworkProcessors(NPUs)+TCAM+DDR

–  NoviFlowNS2128*)•  FlowProcessor

–  NetronomeNFP-4000**)•  ProgrammableSwitchSilicon

–  CaviumXpliant**)*)presentinSURFnettestbed**)sooninSURFnettestbed


Corsa(FPGA/TCAM/DDR3)


CONFIDENTIAL 10

Network Hardware Virtualization

Multiple SDN applications controlling Virtual Switches

Overlay

Hardware Resource Pool

Single piece of hardware

OpenFlow SDN App L3 Routing App

OpenFlow Switch

Any OpenFlow match ANY RateANY PortAny Protocol

L3 Routes + ACLsANY RateANY PortAny Protocol

Underlay

Optimized L3 Router

NoviFlowNS2128

SerD

es

MAC

s

TOPPacket Processors &

Search EnginesTraffic

Manager

OAM

Internal Memory

Classification &Queuing

Internal TCAM

SDRAM DDR3 Controllers


MellanoxEZchipNP-5

NoviFlowPipelineConfiguraLon

•  Setconfigpipeline<id><size><width><type>– <type>isexact(DDR)orwildcard(TCAM)– Default

•  28wildcard+28exacttables•  4096rows•  40bytewide


PipelineAbstracLons

•  FlexibleprogrammablepipelinesneedanabstracLontodescribethem

•  Twopopularapproaches:– TableTypePaQerns(TTP)–OpenFlowpipelines– P4(ProgrammingProtocol-IndependentPacketProcessors)

•  Bothcanbeusedto– LettheswitchadverLseitssupportedpipeline(s)– Telltheswitchwhatpipelinetoconstruct


TableTypePaQerns(TTPs)

•  ATTPisanabstractmodelthatdescribes(inJSONsyntax)theforwardingbehaviour– DescripLonofflowtables– DescripLonofvalidflow_mods,group_modsandmeter_mods

•  SwitchandcontrollermaysupportmulLpleTTPs

•  AtstartupthereisanegoLaLonbetweenswitchandcontrolleraboutwhichTTPtouse


P4Language•  P4:ProgrammingProtocol-IndependentPacketProcessors

•  DomainSpecificLanguageforprogrammabledataplanes

•  P4programàP4compileràtargetcode

•  TargetcodeisloadedonP4switch•  Consistsofpacketparserandlookuptables


P4Switch

INPUT

MatchAction

MatchAction

OUTPUT

ParseGraph

ControlProgram

Match+ActionTable Config

Ingress Egress

Switch Configuration

P4 Switch

PARSER

Queuesand/orBuffers

Source: The P4 Language SpecificationVersion 1.0.2


ExampleP4HeaderDefiniLons

header_typeethernet_t{fields{dstAddr:48;srcAddr:48;etherType:16;}}

header_typeipv4_t{fields{version:4;ihl:4;diffserv:8;totalLen:16;idenLficaLon:16;flags:3;fragOffset:13;Ql:8;protocol:8;hdrChecksum:16;srcAddr:32;dstAddr:32;}}


ExampleP4Parserparserstart{returnparse_ethernet;}parserparse_ethernet{extract(ethernet);returnselect(latest.etherType){ETHERTYPE_IPV4:parse_ipv4;default:ingress;}}parserparse_ipv4{extract(ipv4);returningress;}


P4SupportedTableTypes•  Exact:value==tableentry

–  E.g.IPv4hostroute•  Ternary:valueANDmask==tableentry

– Wildcard•  LPM:LongestPrefixMatch

–  Specialcaseofternary(1111….11110000.....0000)•  Range:lowentry<=value<=highentry•  Valid:tableentry={true,false}

–  True:headerfieldisvalid–  False:headerfieldisnotvalid


P4SupportedChecksumAlgorithms

•  XOR16

•  CSUM16

•  CRC16

•  CRC32

•  Programmable_CRC– ArbitraryCRCpolynomial


AddiLonalP4Features•  Counters

–  Type:bytesorpackets–  Min-width–  SaturaLng:stopcounLng;defaultiswrap

•  Meters

•  Registers

•  Resubmit(originalpacket+metadata)

•  Recirculate(packetaXeregressmodificaLons)


P4ControlFlow•  If/else

•  +,*,-,<<,>>,&,|,^

•  ~,-

•  OR,AND

•  >,>=,==,<=,<,!=


WorkFlow

•  WriteP4program,typicallythesesourcefiles:–  foo.p4– headers.p4– parser.p4

•  ConvertP4programtoJSONconfiguraLon

•  LoadJSONconfiguraLononP4switch


NetworkAbstracLonLayers


Open Switch/Open Network Linux

Broadcom Trident II

OpenNSL

SONiC

White Label Switch

SAI

ProgrammableData Planes

TBD

FBOSSQuagga

Extensions

P4

abstractionlayers

Summary•  OpenFlowstartedthenetworkingdisaggregaLon•  ManycompanieshavejoinedthenetworkingdisaggregaLonefforts

•  Manyopenhardwarevendors•  SeveralopensourcenetworkoperaLngsystemsandrelatedecosystems

•  Variousnewprogrammablenetworksiliconisemerging,TODO:–  fitthissiliconintheopenNOSecosystems– workondesignofopenAPIsandnetworkabstracFons


[email protected]@rvdp.org

hQps://www.rvdp.org@rvdpdotorg


experiences with programmable dataplanes · p4 language • p4: programming protocol-independent...

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