SDN Internet Router (sir)

Matthew Walster matthew at
Fri Jan 6 16:10:56 UTC 2023

On Fri, 6 Jan 2023, 18:38 Mike Hammett, <nanog at> wrote:

> I suspect it always will have value, whether it's peering routers, POP
> routers, multi-homed customer routers, etc.

Indeed. It's not "clean" but it is an acceptable tradeoff if you know what
you're doing, and how traffic sloshes around etc.

I wrote a tool once that took a number of BGP feeds and aggregated the
prefixes based on the next-hop values, which was *amazingly* good at
reducing FIB sizes, but consumed so much CPU and memory, not to mention the
latency of updates during any sizeable churn event, that it proved less
useful than just precomputing based on historical traffic flows and
updating the lists semi-frequently.

The idea of Juniper's EPE etc is very attractive, and largely matches what
I had done back then, but does it with a lot more finesse. Ultimately, it's
a tradeoff between CapEx of the high FIB router and the OpEx of the
engineers who have to maintain the often hacky solution ;)

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