Partial vs Full tables

William Herrin bill at
Mon Jun 8 17:53:07 UTC 2020

On Sun, Jun 7, 2020 at 11:07 PM Saku Ytti <saku at> wrote:
> I'll take my imagination boat from the dry docks and sail to 2035. Lot
> of people still run Jericho ANET, it is the new CAT6500 PFC3. DFZ
> won't fit it anymore without redundant-specifics.
> Are we at all concerned that someone in the DFZ advertises a minimum
> set of prefixes needed to force decompression and if we are, how do we
> protect from it, if we are not, why are we not?

Limit announcements to /24: 2^24 max routes.
Subtract:,,, and some
other reserved networks that don't (or at least aren't supposed to)
show up in the DFZ.

Leaves around 14M routes in the table at full disaggregation to /24.

Current TCAM-based equipment supports 1M - 2M routes. The tech readily
scales 7x just by throwing hardware at it (no redesign). Trie-based
equipment already supports 14M routes with sufficient DRAM and CPU (4
gigs and 2 cores is more than sufficient for a 1 gbps router at the
current 800k routes).

And that's the worst case. The IPv4 table will surely saturate and
stabilize long before 14M routes.

No crisis to avert. Just keep up with your upgrade schedules.

Bill Herrin

William Herrin
bill at

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