Re: [vwrap] VWRAP and IPv6

[David W Levine <[e-mail]>]

[e-mail] wrote on 05/17/2010 10:08:26 AM:

> [image removed] 
> 
> Re: [vwrap] VWRAP and IPv6
> 
> Richard Barnes 
> 
> to:
> 
> Morgaine
> 
> 05/17/2010 10:09 AM
> 
> Sent by:
> 
> [e-mail]
> 
> Cc:
> 
> vwrap
> 
> In the spirit of good layering, it seems like we should be talking 
> about avoiding direct reliance on IP addresses instead of how we can 
> accommodate different addresses in the protocol.  Why is there ever a 
> need to carry an IP address in this application-layer protocol, as 
> opposed to, say, a DNS name or a URI?
> 
> --Richard
> 
+1 

We may from time to time have a IP address stuck in the form of a URI
which has the dotted decimal form of an resource. The spec should make
sure that form can be an IPV6 address, but that should be very straight 
forward. 

There may be some IPV6 features which eventually impact us at the protocol
design level, but the entire VWRAP specification has been written in terms 
of
URIs and Capabilities, not in terms of low level IP addresses. It would 
take an
incredibly powerful argument to suggest that this should change. Likewise, 
while
IPV6 changes addressing at the bottom of the stack, it doesn't appreciably 
change
the cost of holding open sessions, of managing sockets and buffers inside 
of
clients (especially lightweight devices) Further while we can all devoutly 
hope
that IPV6 finally deploys broadly, making it a dependancy in the near term 
feels
rather like a roadblock to possible adoption.

- David
~ Zha



> 
> On May 14, 2010, at 7:32 AM, Morgaine wrote:
> 
> > Despite exceedingly low takeup of IPv6 so far, it's coming, and in 
> > the context of IETF WG rates of progress, it is really imminent.  Of 
> > special relevance to us is that IPv4 addresses are projected to run 
> > out within roughly the same time frame as VWRAP materializes.
> >
> > There is little point in creating a new VW protocol today purely in 
> > the context of IPv4 without thinking about tomorrow's IPv6 
> > environment.  By the time that VWRAP is fully defined, we should 
> > expect a substantial and rapidly increasing proportion of VWRAP 
> > implementations to occur in IPv6-accessible worlds.  This is a 
> > situation for which we need to plan now, otherwise the protocol will 
> > be obsolete before it's even ready.
> >
> > To get the ball rolling, here are a few IPv6-related issues that we 
> > could usefully address in the group:
> >
> >    • The 128-bit IP address of IPv6 is likely to become a common 
> > payload, so it should be supported natively.  LLSD already supports 
> > one 128-bit data type of course, the UUID.  IPv6 addresses should 
> > not be transported in UUID fields however, since their statistical 
> > properties and semantics are totally different.  In any case, the 
> > two spaces are disjoint so confusing them would be a mistake.  The 
> > IPv6 address seems a good candidate for its own defined type, in the 
> > absence of wide integers.
> >    • The extremely large address space of IPv6 has often been 
> > portrayed as allowing everything around us to have its own IP 
> > address.  In the context of virtual worlds, this idea can actually 
> > be put to good use, with each virtual object bearing its own IPv6 
> > address.  One candidate application for this has already been 
> > described in earlier discussions --- for example, implementing 
> > virtual object simulation in two parts, one client-side and one 
> > world-side, the two parts communicating directly.  IPv6 addressing 
> > of objects makes this relatively easy to achieve efficiently, so its 
> > implementation in IPv6-based worlds is almost inevitable before 
> > long.  VWRAP should be ready for this.
> >    • The event queue in current implementations provides an indirect 
> > and highly inefficient way of achieving world-to-client 
> > communications.  IPv6 offers opportunities for direct communication 
> > that can make the event queue approach obsolete, so it's worth 
> > examining IPv6-oriented alternatives.
> >    • We recently discussed feature and protocol negotiation within 
> > VWRAP.  IPv6 provides much opportunity for new features and protocol 
> > pathways to be negotiated between endpoints, so it gives us a very 
> > real and imminent set of use cases for negotiation.
> >
> > It would also be a feather in VWRAP's cap to be considered an "IPv6- 
> > capable application protocol" in a stronger sense than just to be 
> > carried by IPv6 networks.  IPv6 does after all bring new abilities 
> > to the table, such as the huge addressing, and it would be a mistake 
> > to ignore them.
> >
> >
> > Morgaine.
> >
> >
> >
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