[e2e] opening multiple TCP connections getting popular

Bob Briscoe rbriscoe at jungle.bt.co.uk
Thu Aug 30 16:05:16 PDT 2007


At 19:20 30/08/2007, Detlef Bosau wrote:
>Bob Briscoe wrote:
>>This possibly sounds like a misinterpretation of the example I gave in my 
>>(very belated) reply (8 Aug) to your tsvwg email on a similar subject.
>>I explained that the solution I propose doesn't rely on identifiers at 
>>all. It reveals info about congestion being caused downstream in the 
>>headers passing between any two economic entities (whether user and 
>>provider or network to neighbouring network). That matches the pairwise 
>>bilateral contracts people have.
>Do they?

Give an example where they don't?

Trilateral (or worse) contracts are rarely if ever entered into by any 
party with any desire to apportion blame for failings. Note that multiple 
bilateral contracts with different parties for components of the same 
service are still all bilateral.

>And if so, why don´t you use the Congestion Manager (IIRC Seshan et al.?) 
>or similar techniques in those situations?

I assume by "those situations" you mean where an end-user has mulitple 
connections being policed in bulk by her provider.

Indeed, a superficially CM-like object would become v relevant to manage 
the tradeoffs between different connections. But it wouldn't actually be 
doing the same thing as the CM.

The CM was only across connections to the same remote endpoint (I believe), 
to ensure one connection benefited from knowledge other connections had 
gleaned about the same path (although endpoints are never sure two 
connections share the same path because of the prevalence of equal cost 
multipath routing).

The thing that would be needed across all a user's connections in my case 
would be best described as a policy mediator. It would have to track the 
remaining allowance the policer contained and ensure that each connection 
was weighted to get the most out of this policed access over time (taking 
into account how each app might have weighted its own connections). It 
wouldn't need to be monitoring paths like the CM does.


>Detlef Bosau                          Mail:  detlef.bosau at web.de
>Galileistrasse 30                     Web:   http://www.detlef-bosau.de
>70565 Stuttgart                       Skype: detlef.bosau
>Mobile: +49 172 681 9937

Bob Briscoe, <bob.briscoe at bt.com>      Networks Research Centre, BT Research
B54/77 Adastral Park,Martlesham Heath,Ipswich,IP5 3RE,UK.    +44 1473 645196 

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