[e2e] a means to an end
jnc at mercury.lcs.mit.edu
Mon Nov 10 09:09:04 PST 2008
> From: Pekka Nikander <pekka.nikander at nomadiclab.com>
> Date: Sun, 9 Nov 2008 09:25:38 +0200
> Path-specific locators
Let me make sure I understand what you mean by this term. To me, it implies 'a
source route composed of names of only local scope' - whether the 'names'
refer to outbound-interface/next-hop pairs, or local flow names, or whatever,
I don't have any specific concept.
To justify why it seems to me that that's what must be implied,
'path-specific' first seems to imply that the name(s) in it do have local
scope (i.e. a particular path-specific locator refers to two different
destinations, when interpreted at different places in the network). Next,
unless there's *something* in that first local scope which will get that
packet to the ultimate destination based only a single local-scope name (which
I think is unfeasible, for reasons I will discuss below), there must be a
series of these scope-local names - which sounds awfully like a source route.
Is that a correct description of what you visualize them to be? If not, can
you give a bit more detail on what that term implies (in terms of mechanism)
The reason I think that it's infeasible to have a path-specific locator be
composed of only a single local-scope name - e.g. a flow which goes all the
way to the destination - is that that general approach doesn't seem to offer
much, when scaled up to support all possible destinations in the network. For
instance, if they are flows, you'd need to have a full set (to every
destination in the network) at every source in the network - the N^2 problem.
Even if it's not flows, but rather e.g. a translation which turns that
scope-local name into a global locator, the path-specific locator is really
just a security layer which obscures what global locator that scope-local
locator translates to. It can't be much shorter/simpler than a global locator
because that single scope-local locator has to be able to specify the full
range of destinations that can be specified in a global locator.
Or am I missing something?
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