[e2e] Are we doing sliding window in the Internet?

[David Borman]

On Jan 7, 2008, at 4:46 AM, Lars Eggert wrote:

> On 2008-1-6, at 21:51, ext Christian Huitema wrote:
...
>
>>> In that research on "network based" mechanisms, we should accept  
>>> that end systems will be primarily motivated by their self  
>>> interest. They are certainly not motivated by a desire to be fair  
>>> with others. The desire of fairness is a social contract, and I  
>>> don't think we can assume such a contract when the Internet covers  
>>> the entire world. If we could, that would indeed be a good thing,  
>>> we would also have worldwide peace and all that kind of thing. So,  
>>> we have better assume that end system will try to maximize their  
>>> individual satisfaction, rather than looking for the common good.  
>>> If we cannot rely on the benevolent sum of individual behaviors,  
>>> we need to build mechanisms in the network that help it guarantee  
>>> its stability.
>>
>> In fact, ISP are already attempting to build this "stabilization  
>> tools" in their networks. We see various forms of traffic shaping  
>> implemented at bottleneck points. We see various tools used to  
>> perform "traffic engineering". ISP need to do that if they have any  
>> hope of providing some kind of guarantees of service. Many on this  
>> list will find those tools crude, or possibly harmful. Fine, but  
>> the reaction cannot be to retreat in the ivory tower and leer at  
>> those lowly network engineers. Instead of clinging to the illusion  
>> that we can entirely solve the problem in an end to end fashion,  
>> that all end systems will follow the dictate of the E2E group,  
>> maybe we should actually address the problem. What is the best  
>> mechanisms to deploy in the Internet to make it immune to  
>> variations in end to end algorithms?
>
> I agree with you that there'll need to be something that protects  
> the network and other users from selfish end systems, and it will  
> need to be a mechanism that doesn't only rely on the cooperation of  
> those end systems.
>
> But I'm also not convinced that this functionality should completely  
> move into the network, which is what I think ISPs are currently  
> attempting to do. An architecture that gives incentives to the end  
> systems to behave correctly, rather than controlling everything  
> network-side, appears more viable to me. (And we've just gotten some  
> EU money over the next three years to look at how such a system  
> would look in detail.)

The incentive to the end system will always be there: to get useful  
data through to the other side.  "Traffic engineering" can address how  
flows interact/affect each other to avoid network congestion collapse,  
but it is still up to the end system to decide how to make use of  
whatever bandwidth it can get.  There will always be self-interest by  
the end system to avoid having packets lost, and to react sanely when  
there is packet loss to minimize the number of retransmissions.

So I think there will always be a need for both "network engineering"  
and end-to-end solutions.

			-David Borman