[e2e] Do we have buffer bloat on edge routers or on core routers?

Detlef Bosau detlef.bosau at web.de
Tue Apr 2 07:36:24 PDT 2013

Am 02.04.2013 14:58, schrieb Oliver Hohlfeld:
> One reason for the outcome of these studies is that users often do not
> sustainably utilize their uplink capacity and fill-up their potentially
> large queues.

As a quite general remark let me say, that it is not a user's job to 
utilize his uplink capacity. (O.k., some German tabloids and some 
Internet discussions do not so indicate, however, in general it is the 
network's job to serve the user - and never the other way round.)
I've seen quite some papers who stated the contrary and wrote 
sophisticated algorithms to utilize a potential uplink capacity, in my 
opinion this is a completely wrong understanding of computer networking.
>> The primary way that network designers can reduce buffer bloat is
>> over-provisioning.
> This assumes that buffer bloat mainly occurs in the core.
> However, the current evidence suggest it to be a problem
> in the edge: oversized buffers in hosts, 3G, cable / DSL modems
> or home routers have been shown to be often oversized and
> thus have the potential to inject large queueing delays
> when filled.

Perhaps we do not always realize the reason for buffering. In some cases 
we want to harmonize arrival patterns and service patterns, in other 
cases (3G and the like) the purpose of buffering is work conservation. 
Both are valid reasons. The question is whether one and the same buffer 
can successfully and, most of all, in an acceptable manner, serve both 

> To me, buffer bloat is more of a configuration problem than
> a fundamental network problem. The first step in resolving
> buffer bloat should therefore be fixing the misconfigurations
> by deploying reasonable sized buffers in edge equipment.

What is "reasonably sized"? It is particularly this "one size fits all" 
attitude which I think is highly questionable. Buffers may serve 
different purposes and so we should allow for different requirements and 

> This is an initiative that is currently taken in DOCSIS
> standards to give cable operators the chance to tune the
> buffer size in the deployed edge devices.

OMG ;-)

Oliver, admittedly the world has no problems. So, we Germans create one: 
We detect that after the unification we forgot to provide eastern 
Germany with appropriate Internet supply and now we revive commercial 
approaches from the 80s and early 90s.-- 
Detlef Bosau Galileistraße 30 70565 Stuttgart Tel.: +49 711 5208031 
mobile: +49 172 6819937 skype: detlef.bosau ICQ: 566129673 
detlef.bosau at web.de http://www.detlef-bosau.de

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