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Re: [RRG] Geoff Huston's article on BGP stability, update statistics and damping
Noel Chiappa wrote:
While I agree that whatever's causing this ought to be fixed, there are some
points we need to not lose sight of.
First, fixing this would be a *one-time* improvement in the growth curve for
the update rate (versus long-term time). I.e. you'd see a flat spot (or a
drop) in the curve, after which it would resume its previous growth.
Second, 25% is not peanuts, but it's also not an order of magnitude, and
eliminating these wouldn't get us into a whole new operating region. I don't
know what the current growth rate for BGP updates is, but if it's anything
like the growth rate of the table itself (as one might reasonably assume it
is), 25% is not a long calendar time.
Again, it ought to be fixed, but let's not kid ourselves that this is the
solution to our problems.
Actually Noel, I'm not sure that I agree with either of your assertions,
and the basic reason is a lack of an analysis of this over a long term
over a number of years (the data is there, but someone has to set up the
computational run across it). My intuition says that as the degree of
interconnection in the inter-AS cloud increases, then the BGP
"amplification" of underlying events increases, and the same set of
underlying events could be the cause of 26%, 27%,... etc of all updates
in the future. i.e. the querstion in my mind is: are the dynamics we've
been seeing in update load an artifact of the increasing size of the
internet, the increasing interconnection of the Internet, the increasing
level of policy diversity within the Internet or all three - or do all
three growth elements tend to interact with the rather chatty way in
which BGP undertakes convergence to create a long term traffic trend? If
this is the case and if we understand that we really cannot change the
dynamics of the first three elements, then what precisely is the nature
of the interaction with BGP, and is it possible that by altering BGP
update propagation behaviors is it possible to shift the BGP load onto a
different trajectory? Your message says to me: "no, a modification of
BGP creates a short term reduction in update load, but the underlying
growth factors are independent of this." I am not sure that I agree with
this proposition, and more data and more experimentation is probably a
good way to understand this a little better.
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