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Watching the Waist of the Protocol Hourglass

Watching the Waist of the Protocol Hourglass. IETF 51 London August 2001. Steve Deering deering@ cisco.com. email WWW phone... SMTP HTTP RTP... TCP UDP… IP ethernet PPP… CSMA async sonet... copper fiber radio. email WWW phone... SMTP HTTP RTP... TCP UDP… IP

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Watching the Waist of the Protocol Hourglass

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  1. Watchingthe WaistoftheProtocolHourglass IETF 51 London August 2001 Steve Deering deering@ cisco.com

  2. email WWW phone... SMTP HTTP RTP... TCP UDP… IP ethernet PPP… CSMA async sonet... copper fiber radio...

  3. email WWW phone... SMTP HTTP RTP... TCP UDP… IP ethernet PPP… CSMA async sonet... copper fiber radio... Why the Hourglass Architecture? • Why an internet layer? • make a bigger network • global addressing • virtualize network to isolate end-to-endprotocols from network details/changes • Why a single internet protocol? • maximize interoperability • minimize number of service interfaces • Why a narrow internet protocol? • assumes least common network functionalityto maximize number of usable networks

  4. Why Am I Talking About Watching the Waist? • Plenary talk is an opportunity for navel gazing • It happens on reaching middle age (me & IP) • The IP layer is the only layer small enough for me to get my arms around • I am worried about how the architecture is being damaged: the waste of the hourglass • The hourglass theme offers many bad puns

  5. Putting on Weight email WWW phone... SMTP HTTP RTP... TCP UDP… IP + mcast + QoS +... ethernet PPP… CSMA async sonet... copper fiber radio... • requires more functionality from underlying networks

  6. Mid-Life Crisis email WWW phone... SMTP HTTP RTP... TCP UDP… IP4 IP6 ethernet PPP… CSMA async sonet... copper fiber radio... • doubles number of service interfaces • requires changes above & below • creates interoper-ability problems

  7. Oops! AnAccident email WWW phone... SMTP HTTP RTP... TCP UDP… IP ethernet PPP… CSMA async sonet... copper fiber radio... • NATs & ALGsused to glue the broken pieces • lots of kinds of new glue being invented—ruins predictability • some apps remain broken, since repairs are incomplete

  8. Threat-ened by Youths • danger : creeping dependencies on specific link-layers inhibit flexibility and evolution • will never fully supplant IP,so end up with complicated hybrid & more address plans email WWW phone... SMTP HTTP RTP... TCP UDP… IP ATM ethernet CSMA async sonet... copper fiber radio...

  9. But StillSupple • IP-over-IP tunneling has become more and more common • this is not so bad: retains benefits of hourglass model email WWW phone... SMTP HTTP RTP... TCP UDP… IP ethernet PPP… CSMA async sonet... copper fiber radio...

  10. email WWW phone... SMTP HTTP RTP... TCP UDP… IP + ? + ? + ? +... ethernet PPP… CSMA async sonet... copper fiber radio... More Fattening Temptations • TCP “helpers” • reliable multicast assists • packet-intercepting caches • “content-based routing” • active networking

  11. Lost Features of the Internet • transparency • robustness through “fate sharing” • dynamic routing • unique addresses • stable addresses • connectionless service • always-on service • peer-to-peer communication model • application independence

  12. Below-the-Waist Bulge • mostly reinventing, badly, what IP already does (or could do, or should do): • VLANs • LANE (LAN emulation / “interworking”) • layer 2 tunneling protocols • MPLS, PPPoE,… (“layer 2.5”) • lower layers mostly seem to just make IP’sjob harder • cells, circuits, QoS, multicast, large clouds, opaque clouds

  13. What to Do? • First, acknowledge that this is the normal entropy / decay that besets all large, engineered systems over time • So, shall we just let nature take its course? • Or, shall we make the effort to get back into shape?

  14. AFitnessGoal email WWW phone... SMTP HTTP RTP... TCP UDP… IP6 copper fiber radio... • perhaps we can trim down from an hourglass to a wineglass • promising signs:IP-over-SONET, IP-over-WDM • IPv6 to restore simplicity and functionality

  15. OnlyTime Will Tell…

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