Watching the Waist of IETF 51 the Steve London Deering Protocol August deering@ 2001 Hourglass cisco.com 1 email WWW phone... SMTP HTTP RTP... TCP UDP… IP ethernet PPP… CSMA async sonet... copper fiber radio... 2 Why the Hourglass Architecture? 6 Why an internet layer? • make a bigger network • global addressing email WWW phone... SMTP HTTP RTP... • virtualize network to isolate end-to-end TCP UDP… protocols from network details/changes IP 6 Why a single internet protocol? ethernet PPP… CSMA async sonet... • maximize interoperability copper fiber radio... • minimize number of service interfaces 6 Why a narrow internet protocol? • assumes least common network functionality to maximize number of usable networks 3 Why Am I Talking About Watching the Waist? 6 Plenary talk is an opportunity for navel gazing 6 It happens on reaching middle age (me & IP) 6 The IP layer is the only layer small enough for me to get my arms around 6 I am worried about how the architecture is being damaged: the waste of the hourglass 6 The hourglass theme offers many bad puns 4 Putting on email WWW phone... SMTP HTTP RTP... Weight TCP UDP… IP + mcast + QoS +... ethernet PPP… • requires more CSMA async sonet... functionality copper fiber radio... from underlying networks 5 Mid-Life Crisis email WWW phone... SMTP HTTP RTP... TCP UDP… • doubles number of service IP4 IP6 interfaces ethernet PPP… • requires changes CSMA async sonet... above & below copper fiber radio... • creates interoper- ability problems 6 Oops! email WWW phone... • NATs & ALGs An used to glue the SMTP HTTP RTP... broken pieces Accident TCP UDP… • lots of kinds of IP new glue being invented—ruins predictability ethernet PPP… • some apps CSMA async sonet... remain broken, copper fiber radio... since repairs are incomplete 7 Threat- • danger : creeping ened by email WWW phone... dependencies on SMTP HTTP RTP... specific link- layers inhibit Youths TCP UDP… flexibility and evolution IP ATM • will never fully ethernet supplant IP, so end up with CSMA async sonet... complicated copper fiber radio... hybrid & more address plans 8 But Still Supple email WWW phone... SMTP HTTP RTP... TCP UDP… IP • IP-over-IP tunneling has become more and ethernet PPP… more common CSMA async sonet... • this is not so bad: copper fiber radio... retains benefits of hourglass model 9 More Fattening Temptations 6 TCP “helpers” 6 reliable multicast assists 6 packet-intercepting caches 6 “content-based routing” email WWW phone... SMTP HTTP RTP... 6 active networking TCP UDP… IP + ? + ? + ? +... ethernet PPP… CSMA async sonet... copper fiber radio... 10 Lost Features of the Internet 6 transparency 6 robustness through “fate sharing” 6 dynamic routing 6 unique addresses 6 stable addresses 6 connectionless service 6 always-on service 6 peer-to-peer communication model 6 application independence 11 Below-the-Waist Bulge 6 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”) 6 lower layers mostly seem to just make IP’s job harder • cells, circuits, QoS, multicast, large clouds, opaque clouds 12 What to Do? 6 First, acknowledge that this is the normal entropy / decay that besets all large, engineered systems over time 6 So, shall we just let nature take its course? 6 Or, shall we make the effort to get back into shape? 13 A email WWW phone... Fitness • perhaps we can SMTP HTTP RTP... trim down from Goal TCP UDP… an hourglass to a wineglass IP6 • promising signs: IP-over-SONET, IP-over-WDM • IPv6 to restore simplicity and copper fiber radio... functionality 14 Only Time Will Tell… 15.