[RRG] RE: [rr-fs] names vs. addresses

["Dmitri Krioukov" <dima@caida.org>]

exactly! and we know that in the compact routing framework
(which is the most fundamental level of abstraction of routing
problems), name dependence does not buy you much!

indeed, the most surprising finding is that for *generic*
(applicable to all graphs) routing schemes, name-independent
routing can be made as efficient as name-dependent one -- at
least in terms of routing table size vs. stretch trade-off:
in the both cases, you can construct stretch-3 routing schemes
with O(n^{1/2}) routing tables. in other words, you cannot
make routing to perform 'better' by exploiting topology-
sensitive addresses!

of course, you cannot get name-independence from name-dependence
'for free' either. the price is roughly: 1) more algorithmic
complexity; 2) packet headers must be rewritable. it's
straightforward to see why the both points are unavoidable.
(recall the best known results
name-dependent http://www.cs.tau.ac.il/~zwick/papers/route-SPAA.ps.gz
name-independent http://dept-info.labri.fr/~gavoille/article/AGMNT04.pdf.gz )
--
dima.
http://www.caida.org/~dima/


> -----Original Message-----
> From: Kevin Fall [mailto:kfall@EECS.Berkeley.EDU] 
> Sent: Saturday, October 08, 2005 8:49 AM
> To: Joel M. Halpern
> Cc: Dmitri Krioukov; rr-fs@caida.org; rrg@psg.com
> Subject: Re: [rr-fs] names vs. addresses 
> 
> 
> >
> > From:  "Joel M. Halpern" <joel@stevecrocker.com>
> > To:    "Dmitri Krioukov" <dima@caida.org>, <rr-fs@caida.org>
> > cc:    rrg@psg.com
> > Subject: Re: [rr-fs] names vs. addresses
> > Date:  Fri, 07 Oct 2005 23:45:30 EDT
> >
> > ...
> >
> > While that is interesting, most folks looking at that 
> problem tend instead 
> > to look at as a matter of layering.  That is, on one level the 
> > communication is in terms of topologically insensitive 
> names (identities), 
> > and at another layer communication is in terms of 
> toplogically sensitive 
> > names (addresses).
> > Admittedly, this is based on the historically grounded 
> assumption that 
> > routing on the basis of topologically sensitive names is more 
> > effective.  But that does still seem to be a reasonable assumption.
> > some of this is explored in the output of the Name Space 
> Resrach Group.
> > 
> > Yours,
> > Joel
> 
> I think this assumption that is probably the most important one
> to be questioned/investigated at this point in time.
> 
> There is certainly some evidence to suggest that routing
> based on topologically insensitive names is possible and
> reasonably efficient.  That concept has not permeated IETF
> very much.
> 
> The evidence, in my mind, is related to results in the
> DHT/overlay community and also the compact routing work.  The 
> overlay 'evidence'
> however has always troubled me some, because it generally constructs
> arbitrary graphs in a 'convenient' way whereas the compact routing
> work does not.  Also, these communities define the term
> 'stretch' in different ways-- overlay/DHT people tend to define
> it in terms of delay and CR people define it in terms of
> hop count ratios.  The work is cut out for us..
> 
> as the coffee takes effect...
> - K
> 
> > 
> > At 08:43 PM 10/7/2005, Dmitri Krioukov wrote:
> > >several people, including vint cerf at the last sigcomm,
> > >talk about differentiating between node names (or IDs)
> > >and node addresses having some topological sense. i'd
> > >like to emphasize that, at least formally, this distinction
> > >is very well understood, formalized, and researched. it
> > >is directly related to what's called name-independent
> > >routing (working with node "names") vs. name-dependent
> > >routing (working with node "addresses").
> > >
> > >indeed, by definition (http://arxiv.org/abs/cs.NI/0508021),
> > >name-dependent routing embeds some topological information
> > >in node labels which thus cannot be arbitrary, while routing
> > >that can work on the graphs with arbitrary node labels is
> > >called name-independent. thus, networking terms like "node
> > >name" or "node ID" essentially refers to the name-independent
> > >case, while the term "node address" usually implies a
> > >topologically informative node label, i.e., the name-dependent
> > >case.
> > >
> > >even finer classification is considered in 
> http://arxiv.org/abs/cs.DC/990300
> 9
> > >which differentiates the name-dependent case into the two
> > >subcases: node label set is 1...n (case \beta) or completely
> > >arbitrary (case \gamma).
> > >--
> > >dima.
> > >http://www.caida.org/~dima/
> > >
> > >
> > >_______________________________________________
> > >rr-fs mailing list
> > >rr-fs@caida.org
> > >http://rommie.caida.org/mailman/listinfo/rr-fs
> > 
> > _______________________________________________
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> > rr-fs@caida.org
> > http://rommie.caida.org/mailman/listinfo/rr-fs
> 



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