Peer-to-Peer and IPv6 Christian Huitema Architect, Windows Networking Microsoft Corporation

The Internet: a great tool to promote mainframes? Hubert Curien, French Minister of Research, 1993: Having a TCP-IP research network is great. Instead of funding a computer center in each university, we will only need a single large one in Paris. This is not exactly the Internet we had in mind back then…

Enter NAPSTER, and peer- to-peer file sharing  Export the files in an appropriate folder  Announce the file in the central server  Search for interesting target  Retrieve the file in a peer-to-peer manner Client Folder Client 1 export 2 announce NAPSTER 4 download 3 search

Peer-to-peer is the basic design of the Internet Recommended reading: End-to-End Arguments in System Design. Jerome H. Saltzer, David P. Reed, and David D. Clark. But this seems to have been lost in the web…

End-to-end vs. Optimization  Short term problem  Connect many computers,  IP address are expensive  Short term optimization  Use a NAT box,  Hide many computers behind one address  Works well for web clients… Today’s optimizations are tomorrow’s roadblocks !

Making NAPSTER work: global addresses AliceBobCarroll Server

Making NAPSTER work with some firewalls and NAT. AliceBobCarroll Server

In a world of NAT, NAPSTER cannot work! AliceBobCarroll Server

Short term: hack the NAT…  Most NATs support some configuration procedure: “DMZ”, “service host”  We can automate this through UPnP  Discover the NAT  Reserve “port=xxxx” to “host=x.y.z.t”  Consequence for applications:  Use “parameterized” port  Read “port on this system” from a configuration file  Use “global address” in exchanges with peers.

In the medium term, we cannot program all NATs Internet NAT PC API ? By 2002, we will see ISP using layers of NAT. In fact, they do that in China now… We need IPv6 before that! home ISP NAT

Address Shortage is Real! Extrapolating the number of DNS registered addresses shows total exhaustion in But in practice, the “H-ratio” of log10(addresses)/bits reaches 0.26 in 2002.

2002: the end of P2P? As addresses get scarce, ISP can’t get enough allocation, more and more NATs get deployed, and peer-to-peer applications start to break!

We need IPv6, to change the Internet  Addresses are the key  Scarcity: the user is a “client”  Plethora: the user is a “peer”  IPv6 provide enough addressing  format: 1.8E+19 networks, units  assuming IPv4 efficiency: 1E+16 networks, 1 million networks per human  2 networks per sqft of Earth (20 per m 2 )  This enables peer-to-peer!

We can deploy IPv6 !  Applications update?  Use IPv6 for the new applications  Stack upgrade?  Available in W2K, Whistler (developers)  ISP waiting for Cisco?  “6to4” allows automatic deployment over v4  Supported by ICS (Whistler)  Natural evolution of NAT. PC-1 ICS PC-2 PC-3 PC-4 Single v4 IP Advertise v6 prefix

When can we get IPv6? Tech. Preview (W2K) Developers (Whistler) Deployment

More Information on IPv6  Microsoft IPv6 white paper  ork/ipvers6.asp  /library/howitworks/communications/net workbasics/IPv6.asp  Microsoft IPv6 Tech Preview News  ess/2000/Mar00/IPv6PR.asp  Microsoft IPv6 Tech Preview Kit  dks/platform/tpipv6.asp