Subject: Push vs pull vs hybrid, was: Re: [RRG] Mobility considerations in proposal evaluation

From: Iljitsch van Beijnum <[email-masked]>
Date: Wed, 27 Feb 2008 17:46:55 +0100

On 26 feb 2008, at 18:34, Tony Li wrote:

> On the mapping area, we have push systems and pull systems.  Both  
> have substantial drawbacks.  Are there better hybrids?  Are there  
> alternatives?

I think a general model is:

A) you push the information a > 0 part of the way
B) you send the packets a >= 0 part of the way
C) you pull the information a >= 0 part of the way

Fill in the values for A, B and C to your liking, considering that:

- there is a limit to how much and how often you can push
- pulling incurs delays for first packets and other caching issues
- there is very little effective admission control in a distributed  
system so hard to limit growth
- too much pulling is really an inefficient way of pushing
- moving packets without specific routing info increases distance  
traveled, reducing performance and increasing banwdith use

If so inclined, do the above for mapping relationships and for  
reachability separately, rather than making one system that handles  
both, considering that:

* you can guess reachability and be right often, not so much for mapping
* reacting slowly to reachability changes reduces service level a lot
* reacting slowly to mapping changes doesn't automatically reduce  
service level

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From: Dino Farinacci <[email-masked]>
Date: Wed, 27 Feb 2008 15:06:22 -0800

> C) you pull the information a >= 0 part of the way

And are you:

1) Queuing data packets?
2) Dropping data packets?
3) Using data packets as pull-requests?

Dino