[Csci551-talk] LandMark Hierarchy Example

[Yuan Li]

On Thu, 29 Jan 2004, Varun Goel wrote:

> But Yuan if u will carefully see u will notice that router in question
> do have an entry for level 1 router d.i.i  through k so it could have
> routed to  d.i.i instead of d.d.d which seems more appropriate as it is
> just two hops away i.e in the range of d.i.g (r0=2 given)

But g can not say for sure that d.i.i will find a way to t, though in this
case it happens that i has an entry for t.

So in general when g does not have an entry for n, it needs to forward the
packets to upper level router, d in this case.  d for sure has an entry
for n, and the packets can thus be forwarded.


Thanks

Yuan


>
>
> Please clarify...
>
> Thanks
>
> Varun
>
> ----- Original Message -----
>
>
> From: Yuan Li <liyuan at pollux.usc.edu>
> Date: Thu, 29 Jan 2004 13:40:57 -0800 (PST)
> To: Varun Goel <goelvarun at usa.com>
> Subject: Re: [Csci551-talk] LandMark Hierarchy Example
>
> >
> > In the example(Fig 4), d.i.g's routing table does not have an entry for
> > level 1 router n, so it needs to forward the packet to Level 2 router d
> > instead.  And in its routing table, f(not k) is the next hop to reach d.
> >
> > 2.2.5 could help you to better understand routing in Landmark Hierarchy.
> >
> > Thanks
> >
> > Yuan
> >
> >
> > On Thu, 29 Jan 2004, Varun Goel wrote:
> >
> > >  Hi,
> > >
> > > In the Landmark Hierarchy Example given in the research paper they have derived resulting path as 5 hops 1 greater than shortest path but it happened due to the fact that router having no entry for destination forwarded packet to level 2 router which was three hops away but if it had routed the packet to level 1 router which was two hops away and had an entry for it too, it could have resulted in shortest path.
> > >
> > > I am unable to understand why the packet wasnt routed to level 1 router instead?
> > >
> > > Please Clarify if anybody know.....
> > >
> > > Varun
> > > --
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