[e2e] The Internet is too direct (was: [e2e] using p2p overlays to overcome recursive NATs/realms)

[Christian Tschudin]

Jon's initial posting was on NATs and overlays, which I think is an
instance of a more general theme: "indirection".

The Internet is too direct and IP takes too many shortcuts. In fact,
several "enhancements" are reactions to this too direct a style:

- p2p overlays are a reaction to the lack of methods to influence
  routing, run your own address space

- you ask for a web page and get the content from another place

- ping is too direct, smurf likes this, firewalls fight against it

- the "end address" is too direct, mobile IP had to invent its own
  redirection

- peeking at an IP packet's src field to learn about the sender
  is a problematic shortcut that skips a resolution step

- directness also has become an evolution problem: turning the
  standardization knob here alters things allover there - too direct
  coupling

The trend I see is towards requesting and adding more indirection,
for routing, security, economic, transition whatever reason. Not
all of these attempts will be as transparent as the AS thing (another
example of added indirection).

And the architectural consequences? In the long run

- IP becomes an access protocol and emulation target, overlays
  creating partial and transient clouds of emulated directness

- IP "end addresses" become "start addresses" which the network
  has to resolve for you. NAT boxes are just a half step in this
  direction.

christian.


On Fri, 8 Feb 2002, Jon Crowcroft wrote:

> 
> so the problem with most the proposed solutions to workign around nats
> is that they really assume there are only 2 realms - 
> the great unwashed internet, and the poor deprived natted user. 
> 
> the real situation is that packets might traverse multiple natted realms (c.f. realm
> specific ip) - in this scenario, discovering the mapping involves discovering a path of
> several mappings-
> 
> soluton might be to start a p2p service, which propgates mappings - take the ideas from
> stun, turn, rsip etc, and use them repeatedly...where multicast is available use it
> 
> where one can infer the infernal internal algorithm used by a nat, use it. 
> 
> if the p2p service thus built (we might call it an InterNAT) has either dynamic DNS update, or
> uses ipv6 itself, then to provide global reachability is quite simple...
> 
>  cheers
> 
>    jon

---
Christian Tschudin, Uppsala University, IT Dept., Box 325
S-75105 Uppsala, Sweden. http://www.docs.uu.se/~tschudin/