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Evolution of end-to-end: why the Internet is not like any other network

Leslie Daigle, moderator.

Chief Internet Technology Officer

The Internet Society

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Agenda outline

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Overview of the panel

Panelists’ predictions

Panel discussion

Open mic

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Panel overview

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From the IAB’s RFC3724 (2004)

One of the key architectural guidelines of the Internet is the end-to-end principle in the papers by Saltzer, Reed, and Clark [...]. The end-to-end principle was originally articulated as a question of where best not to put functions in a communication system.

Yet, in the ensuing years, it has evolved to address concerns of maintaining openness, increasing reliability and robustness, and preserving the properties of user choice and ease of new service development as discussed by Blumenthal and Clark in [...]; concerns that were not part of the original articulation of the end-to-end principle.”

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Current realities

We still want to build an Internet that features:

!  “increasing reliability and robustness, and preserving the properties of user choice and ease of new service development “

Significant challenges to that include

!  Business evolution

!  Reactions to the revelations of pervasive monitoring –  “Encrypt everything everywhere always” –  Localization of data based on physical geography

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At the heart of the matter

[How] Does the end-to-end principle matter in today’s Internet and going forward?

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The Panel

Leslie Daigle (Moderator)

Fred Baker – network

Andrew Sullivan – infrastructure

Harald Alvestrand – endpoint

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Panelists� predictions

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Fred Baker Network

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End$to$End$principle$•  Mul$ple'statements'in'the'same'paper:'

•  “The$principle,$called$the$end2to2end$argument,$suggests$that$func8ons$placed$at$low$levels$of$a$system$may$be$redundant$or$of$li=le$value$when$compared$with$the$cost$of$providing$them$at$that$low$level.”$–  General'statement'of'the'end5to5end'argument'or'principle'

•  “The$func8on$in$ques8on$can$completely$and$correctly$be$implemented$only$with$the$knowledge$and$help$of$the$applica8on$standing$at$the$end$points$of$the$communica8on$system.$Therefore,$providing$that$ques8oned$func8on$as$a$feature$of$the$communica8on$system$itself$is$not$possible.”$–  This'formula$on'applies'in'cases'in'which'end'system'applica$on'

knowledge'and'help'is'required'to'implement'func$onality'

The$Stupid$Smart$Predictable$Network$•  My'understanding'of'the'End'to'End'principle:'–  One'could'describe'it'as'a'“principle'of'least'surprise”'or'a'“plea'for'simplicity”.'

–  A"lower"layer"should"do"what"an"upper"layer"expects.""•  Operate'correctly'per'the'protocol'•  Recursive!'•  Second5guessing'layers'above,'and'introducing'state,'creates'unintended'consequences'for'operators'and'users.'

–  Lower'layer'performance'enhancements,'implemented'by'including'equivalent'func$onality'in'two'layers,'are'explicitly'allowed;''•  They%should%measurably%enhance%performance…%

Examples$of$things$the$predictable$network$does:$

•  When$handed$a$packet$des8ned$to$a$unicast$or$anycast$address,$it$delivers$the$packet$to$the$address$unchanged$–  It,'however,'intelligently'determines'the'route,'something'the'

applica$on'does'not'do'–  If'it'has'mul$ple'reasonable'routes,'it'uses'them'effec$vely'without'

applica$on'interven$on'

•  It$may$route$traffic$in$a$manner$that$enhances$the$opera8on$and$profit$of$its$administrator$–  Example:'BGP'rou$ng'may'op$mize'the'cost'to'an'administra$on'–  Example:'a'load'balancer'may'balance'load'among'many'hosts'

•  It$operates$transparently$–  When'a'predictable'network'does'something'unusual'with'a'session'or'

packet,'it'tells'the'sender'

Examples$of$things$the$predictable$network$does$not$do$

•  Behave$contrary$to$predic8on,'and'in'so'doing'cause'a'user'or'operator'to'have'to'diagnose'its'behavior'–  When'asked,'in'DNS,'for'the'address'of'party'A,'return'the'address'of'

party'B.'

–  When'given'a'packet'intended'for'delivery'to'party'A,'deliver'it'to'another'party'

–  When'given'a'packet'containing'a'quantum'of'data,'deliver'a'packet'containing'an'unintended'quantum'of'data'

•  Note$that$intermi=ent$behavior$is$contrary$to$predic8on$–  While'it'may'change'its'behavior'(such'as'a'route),'it'doesn’t'oscillate'

The$network$in$2020$•  Simplicity$Principle$

–  “Complexity'is'the'primary'mechanism'which'impedes'efficient'scaling,'and'as'a'result'is'the'primary'driver'of'increases'in'both'capital'expenditures'(CAPEX)'and'opera$onal'expenditures'(OPEX).”''

–  RFC'3439,'quo$ng'Mike'O’Dell'

–  Complexity'is'also'an'enemy'to'security'–'more'things'to'analyze'

•  I$see$some$operators$moving$in$the$direc8on$of$drama8cally$simplifying$their$networks$–  Their'arguments'have'to'do'with'reducing'opera$onal'expense'

–  IPv4'networks'tend'to'be'more'complex'and'less'predictable''than'IPv6,'due'to'NAT'

–  Drama$c'simplifica$on'leads'to'drama$cally'improved'predictability'

•  I$do$not$see$operators,$or$their$vendors,$making$the$network$less$able$to$deliver$value$either$to$its$users$or$its$administra8ons$

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Andrew Sullivan Infrastructure

Isn’t this just the network?

!  Distinguish bits flowing on the wire + basic routing with everything else

!  Infrastructure specialization is unlikely to go away !  Capital expenditure & economies of scale !  “Core business” concerns !  Cattle not pets

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A great compromise

“You got it buddy: the large print giveth, and the small print taketh away” (Tom Waits,

“Step Right Up”) !  Infrastructure providers rely on something like

Fred’s “predictable network” !  Infrastructure providers have to alter their

behaviour depending on the user !  They’re all doing this at once

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Know your customer in 2020

!  Technologies that give hints will be embraced !  Identify certain properties of network user !  Correlate user across different services !  Not very end-to-endy

!  Technologies that are invasive with be eschewed !  Customers hate intrusion !  Corner cases == support costs == no profit !  End-to-endy

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Wishful thinking

!  Protocol development provides exactly enough hint to do good, and not enough to do harm.

!  The cracks in “network neutrality” don’t become a complete breach.

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Harald Alvestrand Endpoint

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General discussion

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At the heart of the matter

[How] Does the end-to-end principle matter in today’s Internet and going forward?

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