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Watching the Waist of the Protocol Hourglass

Watching the Waist of the Protocol Hourglass. Steve Deering deering@ cisco.com. ICNP ’98 Austin, TX October 14, 1998. The Internet Protocol Hourglass. email WWW phone... SMTP HTTP RTP... TCP UDP … IP ethernet PPP … CSMA async sonet... copper fiber radio.

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Watching the Waist of the Protocol Hourglass

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  1. Watchingthe WaistoftheProtocolHourglass Steve Deering deering@ cisco.com ICNP ’98 Austin, TX October 14, 1998

  2. The Internet Protocol Hourglass 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? • Keynote 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 now being lost: 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 • major interoper-ability issues

  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 • doesn’t fully supplant IP, so end up with complicated hybrid & two address plans email WWW phone... SMTP HTTP RTP... TCP UDP… IP ATM ethernet CSMA async sonet... copper fiber radio...

  9. The Youths’ Latest Trick email WWW phone... SMTP HTTP RTP... TCP UDP… IP ATM CIF ethernet PPP… CSMA async sonet... copper fiber radio... • cells-in-frames (CIF) • shredded and bundled packets • hope is that IP and frame-oriented media will fade away • goal is a fatter waist

  10. email WWW phone... SMTP HTTP RTP... TCP UDP… IP + ? + ?... ethernet PPP… CSMA async sonet... copper fiber radio... More Fattening Temptations • layer 2 tunneling protocols • TCP “helpers” • reliable multicast assists • “content-based routing” • active networking

  11. Below-the-Waist Bulge • mostly reinventing, badly, what IP already does (or could do): • VLANs • LANE • router bypass / NHRP • tag-switching / MPLS (“layer 2.5”) • lower layers mostly seem to just make IP’sjob harder • cells, circuits, QoS, multicast, large clouds, opaque clouds

  12. Obfuscation • In case all this didn’t make the network manager’s job hard enough… • we renamed bridges to switches • we renamed routers to switches • we now have “multilayer switches” and “layerless switches”

  13. Entropy or Evolution? • looks like the normal entropy (decay) that besets all large, engineered systems over time • don’t know where/how to reapply energy to fight the entropy • less worrisome to view as evolution instead • the Internet as an evolving lifeform or ecosystem? • just let nature (the market) take its course • though result is undesigned and unpredictable, should not be viewed as decay

  14. Survival of the Fittest? email WWW phone... SMTP HTTP RTP... TCP UDP… IP6 copper fiber radio... • may evolve from an hourglass to a wineglass • early signs:IP-over-SONET, IP-over-WDM • need IPv6 to restore slim waist

  15. OnlyTime Will Tell…

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