estimation of number of DFZ IPv4 routes at peak in the future

William Herrin bill at
Fri Mar 11 19:43:13 CST 2011

On Fri, Mar 11, 2011 at 6:39 PM, Justin Krejci <jkrejci at> wrote:
> On Wed, 2011-03-09 at 09:32 -0500, John Curran wrote:
>> On Mar 9, 2011, at 12:43 AM, Majdi S. Abbas wrote:
>> >    I suspect that as we reach exhaustion, more people will be
>> > forced to break space out of their provider's v4 aggregates, and
>> > announce them, and an unfiltered DFZ may well approach the 'million'
>> > entries some vendors now claim to support.
>> This matches my personal view (and could be viewed as
>> "success" compared to the 5M estimate of Mr. Herrin...)
> Are people going to be relying on using default-routing then in the
> future if they don't upgrade routers to handle large routing table
> growth? Or perhaps forgo dual-stack and have a separate physical IPv6
> BGP network from IPv4? Are there any other strategies?

Hi Justin,

IMHO, the most sensible strategy is to recognize that that cost of a
route has been dropping faster than the route count has been rising
for the past decade. Then recognize that with today's hardware,
building a route processor capable of keeping up with 10M routes
instead of 1M routes would cost maybe twice as much... 10M being
sufficient to handle the worst case estimates for the final size of
the IPv4 table in parallel with any reasonable estimate of the IPv6
table in the foreseeable future. Better CPU, more DRAM, bigger TCAM.
It could be built today.

Finally, get mad at your respective router manufacturers for
engineering obsolescence into their product line by declining to give
you the option.

But that's just my opinion...

Bill Herrin

William D. Herrin ................ herrin at  bill at
3005 Crane Dr. ...................... Web: <>
Falls Church, VA 22042-3004

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