Mike Hammett wrote:
I'm not concerned with which technology or buzzword gets the job done,
only that the job is done.
Looking briefly at the couple of things out there, they're evaluating
the top X prefixes in terms of traffic reported by s-flow, where X is
the number I define, and those get pushed into the FIB. One
recalculates every hour, one does so more quickly. How much is
appropriate? I'm not sure. I can't imagine it would *NEED* to be done
all of that often, given the traffic/prefix density an eyeball network
will have. Default routes carry the rest. Default routes could be
handled outside of this process, such that if this process fails, you
just get some sub-optimal routing until repaired. Maybe it doesn't
filter properly and sends a bunch of routes. Then just have a prefix
limit set on the box. Maybe it sends the wrong prefixes. No harm, no
foul. If you're routing sub-optimally internally, when it does hit a
real router with a full FIB, it gets handled appropriately.
Unless it loops.
The rest sounds nice. But flow caching got a bad rap back in the early
worm days. But thats because the situation was a little worse back then.
Cache the wrong routes or run out of cache, router dies. So long as
thats not the case automating optimization is an extremely valuable goal.
I would just be looking for solutions that influence what's in the FIB
and let the rest of the router work as the rest of the router would.
The problem comes when the router wont work at all without the FIB
routes, like in the olden days.
-----
Mike Hammett
Intelligent Computing Solutions <http://www.ics-il.com/>
<https://www.facebook.com/ICSIL><https://plus.google.com/+IntelligentComputingSolutionsDeKalb><https://www.linkedin.com/company/intelligent-computing-solutions><https://twitter.com/ICSIL>
Midwest Internet Exchange <http://www.midwest-ix.com/>
<https://www.facebook.com/mdwestix><https://www.linkedin.com/company/midwest-internet-exchange><https://twitter.com/mdwestix>
The Brothers WISP <http://www.thebrotherswisp.com/>
<https://www.facebook.com/thebrotherswisp><https://www.youtube.com/channel/UCXSdfxQv7SpoRQYNyLwntZg>
------------------------------------------------------------------------
*From: *"Christopher Morrow" <morrowc.li...@gmail.com>
*To: *"Mike Hammett" <na...@ics-il.net>
*Cc: *"Tom Beecher" <beec...@beecher.cc>, "NANOG" <nanog@nanog.org>
*Sent: *Thursday, January 5, 2023 12:27:08 PM
*Subject: *Re: SDN Internet Router (sir)
On Thu, Jan 5, 2023 at 11:18 AM Mike Hammett <na...@ics-il.net
<mailto:na...@ics-il.net>> wrote:
Initially, my thought was to use community filtering to push just
IXes, customers, and defaults throughout the network, but that's
obviously still sub-optimal.
I'd be surprised if a last mile network had a ton of traffic going
to any more than a few hundred prefixes.
I think in a low-fib box at the edge of your network your choices are:
"the easy choice, get default, follow that"
"send some limited set of prefixes to the device, and default, so
you MAY choose better for the initial hop away"
you certainly can do the second with communities, or route-filters
(prefix-list) on the senders, or....
you can choose what prefixes make the cut (get the community(ies))
based on traffic volumes or expected destination locality:
"do not go east to go west!"
these things will introduce toil and SOME suboptimal routing in some
instances... perhaps it's better than per flow choosing left/right
though and the support calls related to that choice.
In your NOLA / DFW / ATL example it's totally possible that the
networks in question do something like:
"low fib box in tier-2 city (NOLA), dfz capable/core devices in
tier-1 city (DFW/ATL), and send default from left/right to NOLA"
Could they send more prefixes than default? sure... do they want to
deal with the toil that induces? (probably not says your example).
SDN isn't really an answer to this, though.. I don't think. Unless you
envision that to lower the toil ?
