Hi,
I believe that using caches (using regular clients on dedicated well
placed machine) makes sense to
reduce last miles traffic.
However, I do not see a scenario in which caches are useful (here I mean
that they cannot be replaced by
a real P2P client with an appropriate locality definition used by the
P2P protocol because the ISP architecture
prevent real P2P clients to be located at an appropriate location)
without requiring a large number of such caches.
In particular, deploying such caches can be much more expensive that
what you present.
If you take for instance the case of a DSL provider, you need to place
one dedicated cache per DSLAM.
As there is a lot of DSLAM for a single ISP (hundreds to thousands) the
cost is not negligible.
One may argue that even a few millions of dollars is not significant for
an ISP, but if it is to reduce a cost shift
from content providers to network providers, it might be hard to
convince ISPs that it is up to them to invest
in a new infrastructure.
Do you have in mind specific scenarios in which few caches can save a lot
of last mile traffic, or did I misunderstood your proposition.
Regards,
Arnaud.
Nicholas Weaver wrote:
http://www.ietf.org/internet-drafts/draft-weaver-alto-edge-caches-00.txt
I just submitted a new draft on why I think P2P edge caches are
necessary, and how localization interacts with edge-caches.
Among other things, edge-cache support requires associating filename
information with requests (and therefore has privacy implications), etc.
Abstract:
Without caches in the infrastructure, peer to peer content delivery's
primary effect is cost shifting rather than cost savings. Even with
perfect localization, depending on the relative cost of last-mile
uplink bandwidth verses transport bandwidth, P2P may substantially
increase aggregate cost. Yet the addition of edge caches, caches
located in the ISPs near the customers, radically change the
economics of P2P content delivery. Edge caches interact very
strongly with localization services for P2P content delivery, and any
localization service must be tightly integrated into edge-cache
operation.
Comments greatly appreciated.
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Arnaud Legout, Ph.D.
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