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This looks good, but I think it would be imprudent to deploy it  
without simulating it.  Is there an easy way we could simulate this?

Ian.

On 13 Apr 2006, at 07:12, Matthew Toseland wrote:

> Yes, it might. I like your suggestion, but need some feedback from Ian
> on it.
>
> On Thu, Apr 13, 2006 at 01:59:02PM +0100, Michael Rogers wrote:
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>> Matthew Toseland wrote:
>>> Yep. One request send rate for all neighbours combined.
>> ...
>>> If it's local, it backs off. Either way it reduces its overall send
>>> rate via AIMD.
>>
>> This seems like it might lead to a chain reaction: when a request is
>> rejected, all nodes along the path reduce their rate for all  
>> neighbours,
>> causing queues to fill up and additional requests to be rejected. For
>> example:
>>
>>     E
>>     |
>> A---B---C---D
>>     |
>>     F
>>
>> A sends a request along the path ABCD. D rejects the request because
>> it's overloaded, so B and C reduce their rates. E's request along the
>> path EBF gets rejected because B has reduced its rate, even though  
>> none
>> of the nodes along EBF is overloaded.
>>
>> Here's what I'd suggest instead:
>>
>> * Keep a separate rate for requests to each neighbour
>> * Decrease the rate when a _local_ RejectedOverload is received
>> * Send a RejectedOverload if the queue is full
>>
>> In the example above, only C's rate to D would be reduced  
>> initially, but
>> if A continued to send requests at a high rate then C's queue to D  
>> would
>> fill up and it would send a RejectedOverload to B, which would reduce
>> its rate to C, and so on until A's traffic was quenched. The traffic
>> along EBF would be unaffected.
>>
>> Backoff seems to be redundant under this scheme...
>>
>> Cheers,
>> Michael
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>
> -- 
> Matthew J Toseland - toad at amphibian.dyndns.org
> Freenet Project Official Codemonkey - http://freenetproject.org/
> ICTHUS - Nothing is impossible. Our Boss says so.

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