Sebastian,
How would you see the tracker doing that? Would it really merge maps from
N separate ALTO servers into one master map? Given that each ALTO server
can define PIDs however it wants, is that even possible?
Or do you see the tracker as maintaining copies of each of the N ALTO cost
maps separately, and using the one that is closest to the requesting peer?
Eg, when a New York peer asks for peers, the tracker uses the cost map
from the ALTO server nearest New York. For a Tokyo peer, the tracker uses
the cost map from the ALTO server nearest Tokyo. Then the individual maps
wouldn’t be as large. But there would be a lot of them. And the tracker
would have to decide which map to use. Perhaps it could use the network
map which has the finest detail around the requesting peer’s address?
Whatever that means?
Yet another approach would be for the tracker to require each peer to
provide the uri for its local ALTO server. The tracker would send an ECS
to that ALTO server to evaluate the costs of the other peers. Of course,
then the tracker must make an ALTO query for every peer request, which
will add a lot of latency to each request.
Although ... heh heh ... that could be one way for a tracker to do
cross-domain ALTO server discovery!
- Wendy
On 07/11/2014, 13:56, "Sebastian Kiesel" <[email protected]> wrote:
>Hi Wendy,
>
>this is very true! But the question is, from where does the tracker get
>the 5000x5000 matrix, if there is no single ALTO server that provides it?
>
>One answer may be that the tracker will have to query multiple ALTO
>servers and assemble the map on its own. (That's why I am working on and
>lobbying for cross-domain discovery alias 3pdisc for quite a long
>time...) But in this case the maps pulled from the individual ALTO
>servers would be smaller, and the tracker could control the update
>intervals individually.
>
>Sebastian
>
>
>
>On Fri, Jul 11, 2014 at 01:44:54PM -0400, Wendy Roome wrote:
>>I don¹t know whether any ALTO server could maintain a full 5000x5000 cost
>>matrix, but I can give you a very reasonable example of a client who like
>>one.
>>Consider a large P2P tracker. It has thousands of peers for each file,
>>scattered over the planet. It gets lots of requests from peers, who are
>>also scattered all over the planet. When a peer in New York asks for
>>peers, the tracker needs the costs from New York to every other peer. And
>>the tracker needs detailed local costs for the New York area: for a New
>>York peer, Boston is better than Chicago, and Chicago is better than San
>>Francisco. But to a New York peer, Tokyo & Kyoto are the same.
>>But when the tracker gets a request from a Tokyo peer, the tracker needs
>>detailed local cost data for Tokyo & Japan. For that peer, Tokyo is
>>better
>>than Kyoto � and Boston and New York are the same.
>>So a large P2P tracker love to have a fully populated 5k x 5k cost
>>matrix.
>> - Wendy
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