[e2e] Do we have buffer bloat on edge routers or on core routers?
detlef.bosau at web.de
Thu Mar 28 12:31:00 PDT 2013
Am 28.03.2013 19:38, schrieb Oliver Hohlfeld:
>> Perhaps my question is a stupid one, however, can someone help me here?
> While there is a lack of evidence, I tend to believe the answer
> is no for most networks.
> Let me briefly elaborate on this issue. It is hard to provide a
> definite answer due to the multitude of possible devices and
> configurations. I tried conducting a survey of typical hardware
> combinations and talk to more operators, but had to give up at some
> Signs of buffer bloat:
> - I remember having read reports of queuing delays of up to
> one second in the Level 3 network. Unfortunately, I can't
> find the reference any more.
> Contra buffer bloat:
Sounds a bit as if buffer bloat is rarely "directly observed" but
typically concluded from symptoms?
> - By working with a tier-1 network, I never found evidence for potential
> buffer bloat in their core and aggregation network (might be
> different for other networks). The aggregation network has been put
> under load and none of the devices showed excessive queuing. In
> fact, queuing delays were minimal.
> In the core, the buffers are "reasonably" sized and don't allow for
> excessive queuing.
Hence, buffer bloat is anticipated by appropriate network design here?
In other words: The tier-1 network is designed that way that tier-1
routers hardly are the bottlenecks for any flow?
> - Typical buffer sizes are around 100ms. Juniper "M-Series" routers
> are at 200ms.
> - While it is theoretically possible to have bloated buffers in the
> core, affording excessive buffering is getting more expensive /
> infeasible with increasing line card speed (e.g., 100GE).
> - The switching infrastructure in the aggregation network is
> typically not equipped with a lot of buffer space.
> In conclusion, from what I have seen so far, I believe that buffer
> bloat is mostly a problem at the edge.
70565 Stuttgart Tel.: +49 711 5208031
mobile: +49 172 6819937
detlef.bosau at web.de http://www.detlef-bosau.de
More information about the end2end-interest