I think whatever the centralized or distributed tracker you chose,
if you must deal with billions of users's access, they're the same. The
centralized tracker must be deployed in distributed or so-called 'cluster'
mode, DHT is just one kind of distributed algorithm, not so special...
And futhermore, the DHT algorithm does not always mean 'poor
performance', we have implemented one kind of DHT algorithm suitable for
stable network, its lookup cost is one hop(thousands nodes) or two
hop(millions nodes), and the algorithm released as a plug-in of RELOAD
protocol.
The similar algorithm you can found in amazon's dynamo or the
memcahce project, and there's also some other constant complexity DHT
algorithm.
Russell Wang
jc <[email protected]>
发件人: [email protected]
2010-03-16 08:58
收件人
Bruce Lowekamp <[email protected]>
抄送
"[email protected]" <[email protected]>
主题
Re: [P2PSIP] Is P2PSIP RELOAD not suitable to be leverage for both P2P
Live Streaming and VoD Service?
The largest overlay i've seen where every node participated in storage and
routing was ~1.6M. They operate best under ~650K. At about 1M the routing
times get into the minutes. You would need to create and ad-hoc overlay
for every stream. I've implemented a multicast layer that does this over a
DHT. The DHT is the signaling layer used to setup these ad-hoc
overlays(groups). RELOAD could perform the signaling, rendezvous setup,
multicast grouping storage but not too much more.
On Mar 15, 2010, at 8:10 PM, Bruce Lowekamp wrote:
So substituting the terms used in RELOAD, this is exactly my point.
draft-hu-ppsp-tracker-dht-performance-comparison assumes 20M peers, i.e.
nodes used in routing, and bases latency calculations on that number. Not
57K. The draft further works out that with 20M peers storing data, each
needs to store 0.01 of a resource.
Even if you do the calculations with a reasonable number of peers (routing
nodes), the dht overlay will still obviously have higher latency than a
single-server based solution. You select a dht overlay for different
reasons than you would select a central server-based solution.
Bruce
On Mon, Mar 15, 2010 at 3:27 PM, jc <[email protected]> wrote:
You need 57,142.857 nodes to route 20M of peer traffic. This is the
algorithm we used in fasttrack and is the same as in skype. This is a
maximum capacity scenario.
Sent from my iPhone
On Mar 15, 2010, at 6:32 PM, Bruce Lowekamp <[email protected]> wrote:
They scale fine, but there is a point beyond which adding additional peers
to the overlay routing merely adds latency. Don't have time to look up
the references now, but there are a number of papers discussing the
advantages of different numbers of peers (superpeers in a lot of systems)
needed for overlay routing. You don't need 10M.
Bruce
On Mon, Mar 15, 2010 at 11:55 AM, jc <[email protected]> wrote:
On Mar 15, 2010, at 3:32 PM, Bruce Lowekamp wrote:
The performance comparison draft compares the performance of a centralized
lookup server with a P2P DHT system with 10M peers. Since those address
entirely different use cases, and no one would ever deploy a 10M peer
distributed tracker, it's not clear what the point of the comparison is.
This has nothing to do with RELOAD.
There are active distributed trackers w/ > 1M peers. Why would you not
deploy a 10M user distributed tracker? They do inherently scale infinitely
by nature.
Bruce
On Mon, Mar 15, 2010 at 12:55 AM, World <[email protected]> wrote:
Dear all,
I am thinking what P2P Live Streaming and VoD Service can leverage P2PSIP
RELOAD. According to some research or proposal report, it seems that
P2PSIP RELOAD can be used in P2P-based Tracker and/or chunk description
distribution (chunk discovery) at the full distributed deployment. Both
P2P-based Tracker and chunk description distribution over P2PSIP overlay
were evaluated in performance referred to
draft-chen-ppsp-dht-chunk-discovery-evaluation-00.txt and
draft-hu-ppsp-tracker-dht-performance-comparison-01.txt. The result showed
the performance of DHT-based Tracker and chunk description distribution is
worse, even not acceptable for P2P Live Streaming and VoD Service.
So can we make such conclusion that P2PSIP RELOAD is not suitable to be
leverage for both P2P Live Streaming and VoD Service in case a full
distributed deployment is not mandatory? What do you think?
Any comments are welcome. Thanks.
BR,
Jeffrey
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