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Re: And Now for Something Completely Different (was Re: IPv6 news)

  • From: Mark Smith
  • Date: Sun Oct 16 04:05:47 2005

Hi David,


> Well, if you NAT the destination identifier into a routing locator  
> when a packet traverses the source edge/core boundary and NAT the  
> locator back into the original destination identifier when you get to  
> the core/destination edge boundary, it might be relevant.  The  
> advantages I see of such an approach would be:
> - no need to modify existing IPv6 stacks in any way
> - identifiers do not need to be assigned according to network  
> topology (they could, in fact, be allocated according to national  
> political boundaries, geographic boundaries, or randomly for that  
> matter).  They wouldn't even necessarily have to be IPv6 addresses  
> just so long as they could be mapped and unmapped into the  
> appropriate locators (e.g., they could even be, oh say, IPv4 addresses).
> - locators could change arbitrarily without affecting end-to-end  
> sessions in any way
> - the core/destination edge NAT could have arbitrarily many locators  
> associated with it
> - the source edge/core NAT could determine which of the locators  
> associated with a destination it wanted to use
> Of course, the locator/identifier mapping is where things might get a  
> bit complicated.  What would be needed would be a globally  
> distributed lookup technology that could take in an identifier and  
> return one or more locators.  It would have to be very fast since the  
> mapping would be occurring for every packet, implying a need for  
> caching and some mechanism to insure cache coherency, perhaps  
> something as simple as a cache entry time to live if you make the  
> assumption that the mappings either don't change very frequently and/ 
> or stale mappings could be dealt with.  You'd also probably want some  
> way to verify that the mappings weren't mucked with by miscreants.   
> This sounds strangely familiar...

Certainly does. Apparently this or a similar idea was suggested back in
1997, and is the root origin of the 64 bits for host address space,
according to Christian Huitema, in his IPv6 book -

A google search found the draft :

"GSE - An Alternate Addressing Architecture for IPv6"

> Can two evils make a good?  :-)

Not sure, however, two wrongs don't make a right, but three lefts do.



        The Internet's nature is peer to peer.