nanog mailing list archives

Re: SDN Internet Router (sir)


From: Tom Beecher <beecher () beecher cc>
Date: Wed, 4 Jan 2023 08:36:58 -0500

Disagree that it’s a line in the sand. It’s use the right tool for the job.

If a device is low FIB, it’s that way for a reason. There are plenty of
ways to massage that with policy and software, depending on capabilities ,
but at the end of the day, trying to sort 10 pounds of shit to store in a 5
pound bag is eventually going to end up the same way.

On Tue, Jan 3, 2023 at 13:18 Mike Hammett <nanog () ics-il net> wrote:

There are likely more networks with 10 gigabit or less total external
capacity than there are with more.

Creating imaginary lines in the sand doesn't really help anyone.




-----
Mike Hammett
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------------------------------
*From: *"Mel Beckman" <mel () beckman org>
*To: *"Mike Hammett" <nanog () ics-il net>
*Cc: *"NANOG" <nanog () nanog org>
*Sent: *Tuesday, January 3, 2023 10:57:34 AM
*Subject: *Re: SDN Internet Router (sir)

It’s not a problem, due to cheap, plentiful high-speed memory and rapid
prefix search silicon in backbone routers. The entire Internet routing
table consumes at most a few gigabytes when fully structured (and only a
few hundred Mbytes stored flat).  That’s less memory than your average
laptop sports.


Even in the worst case scenario, where every network decides to announce
only its most specific prefixes, the BGP backbone would temporarily enter
an oscillating state that generates a large number of routing updates into
the inter-domain routing space. In this case, BGP route damping will
quickly suppress the crazies while  the backbone stabilizes.


Small routers should not be taking full tables, since there is no point to
them being in the default free zone. For large routers, neither memory nor
CPU speed are an issue. High-speed routers operating in the default-free
zone have a critical path in the forwarding decision for each packet: it
needs to take less than the inter-packet arrival time for minimum-sized IP
packets.


This is easy to achieve with today’s hardware. A router line card with an
aggregate line rate across all of its point-to-point interfaces of 10Tbps
(readily available in today’s gear) can process packets with just a handful
of cycles in the FIB Ternary Content Addressable Memory (TCAM) using
ASIC-assisted lookups. TCAM is the most expensive component you’re paying
for in such a router.  It’s not cheap,  but backbone routers don’t need
to be cheap. They just need to not be memory-constrained.

-mel via cell

On Jan 3, 2023, at 7:47 AM, Mike Hammett <nanog () ics-il net> wrote:


https://github.com/dbarrosop/sir

I came across this over the weekend. Given that the project was abandoned
six years ago, are there any other efforts with a similar goal (more
intelligently placing routes into FIBs of low-FIB capacity devices?



-----
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>




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