Re: Re: Semi-Reliable UDP Layer

Michael Green <[email protected]> Mon, 24 Sep 2012 17:05:39 +0100
Newsgroups	gmane.network.gnutella.devel
Message-ID	<[email protected]>
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That's more along the lines I was thinking, yes. But moreso, because
it's working with ACKs instead of NAKs, I think that might lead to
scalability issues down the line (exactly as you said, the packet is
assumed lost and will be retransmitted - opposed to waiting for an
acknowledgement of which packets have/have not been received). With
today's overall reliability of Internet connections, that seems
unnecessary.

On 23/09/12 21:50, [email protected] wrote:
> Quoting Michael Green <[email protected]> from ml.gnutella.dev-forum:
> :When are acknowledgements expected? It seems to me that your extended
> :acknowledgement would me much more efficient, rather than
> :acknowledgement per fragment, even when the fragment count is less than 3.
> 
> Indeed.
> 
> I actually had this idea of using a Nagle-like algorithm:
> 
> - Each time a fragment is received, rearm a 100 ms (say) timer.
> - Once the timer fires, acknowledge what's been received so far.
> 
> In other words, delay the acknowledgment a bit in the hope that more
> fragments for the same packet will arrive.
> 
> That shouldn't make a difference for the sender, but it will save bandwidth
> on the recipient's side and maximize the chances of being able to only
> do a Cumulative Acknowledgement.
> 
> One cannot delay acks too much though because otherwise the sender will
> think the packet has been lost and it will retransmit.
> 
> Is that what you had in mind as well?
> 
> Raphael

-- 
Mike Green

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      <p>That's more along the lines I was thinking, yes. But moreso, because<br>
it's working with ACKs instead of NAKs, I think that might lead to<br>
scalability issues down the line (exactly as you said, the packet is<br>
assumed lost and will be retransmitted - opposed to waiting for an<br>
acknowledgement of which packets have/have not been received). With<br>
today's overall reliability of Internet connections, that seems<br>
unnecessary.<br>
<br>
On 23/09/12 21:50, <a href="mailto:Raphael_Manfredi%40pobox.com">[email protected]</a> wrote:<br>
&gt; Quoting Michael Green &lt;<a href="mailto:myatus%40gmail.com">[email protected]</a>&gt; from ml.gnutella.dev-forum:<br>
&gt; :When are acknowledgements expected? It seems to me that your extended<br>
&gt; :acknowledgement would me much more efficient, rather than<br>
&gt; :acknowledgement per fragment, even when the fragment count is less than 3.<br>
&gt; <br>
&gt; Indeed.<br>
&gt; <br>
&gt; I actually had this idea of using a Nagle-like algorithm:<br>
&gt; <br>
&gt; - Each time a fragment is received, rearm a 100 ms (say) timer.<br>
&gt; - Once the timer fires, acknowledge what's been received so far.<br>
&gt; <br>
&gt; In other words, delay the acknowledgment a bit in the hope that more<br>
&gt; fragments for the same packet will arrive.<br>
&gt; <br>
&gt; That shouldn't make a difference for the sender, but it will save bandwidth<br>
&gt; on the recipient's side and maximize the chances of being able to only<br>
&gt; do a Cumulative Acknowledgement.<br>
&gt; <br>
&gt; One cannot delay acks too much though because otherwise the sender will<br>
&gt; think the packet has been lost and it will retransmit.<br>
&gt; <br>
&gt; Is that what you had in mind as well?<br>
&gt; <br>
&gt; Raphael<br>
<br>
-- <br>
Mike Green<br>
</p>

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