The conclusion earlier work on congestive response routing reached was
that one needed to pin the specific routing decision until the selected
path became infeasible.
Yours,
Joel
On 12/4/18 10:59 AM, Spencer Dawkins at IETF wrote:
Hi, Stewart,
On Tue, Dec 4, 2018 at 6:07 AM Stewart Bryant <[email protected]
<mailto:[email protected]>> wrote:
On 30/11/2018 19:23, Spencer Dawkins at IETF wrote:
This is Mirja's comment, but ...
On Fri, Nov 30, 2018 at 10:12 AM Mirja Kühlewind
<[email protected] <mailto:[email protected]>> wrote:
Mirja Kühlewind has entered the following ballot position for
draft-ietf-opsawg-ipfix-bgp-community-11: No Objection
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----------------------------------------------------------------------
COMMENT:
----------------------------------------------------------------------
One comment on section 1:
"For example, they can shift some flows
from congested links to low utilized links through an SDN
controller
or PCE [RFC4655]."
I'm not aware that ipfix information is commonly used for
dynamic traffic
adaptation and I'm not sure that is recommendable. C
I'm agreeing with Mirja here.
We've spent a LOT of time not recommending dynamic traffic
adaptation. Probably half my responsibility as AD for ALTO was
repeating "you can't react based on changes to that attribute
without taking chances on oscillation" like it was a mystical
incantation, and I wasn't the first AD to have that conversation
repeatedly.
Yes, I understand the ARPA net had exactly that problem at one stage
and had to be converted from using a delay based metric to a fixed
metric.
I would be happy to hear that all those problems are solved, but I
haven't heard that yet. Do the right thing, of course.
Even "can shift some flows from persistently congested links to
underutilized links" would cause me less heartburn.
There is no such thing as permanent in network paths!
Like many control problems the first order solution is to damp with
a suitably long time constant, but infinity, i.e. permanent, is not
a satisfactory choice either.
Yeah, that's where I was headed (stated more coherently).
Saying "I should do something, because the network path is STILL
congested" is safer than "I should do something because the network path
is congested", so now we're talking about suitable definitions of
"STILL". I was shooting for that with "persistent", and agree that
"permanent" path characteristics is a happy idea we aren't likely to see
in practice.
Do the right thing, of course ;-)
Spencer
- Stewart
Spencer
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