IP4 Space
Owen DeLong
owen at delong.com
Tue Mar 23 07:40:00 UTC 2010
On Mar 22, 2010, at 10:27 PM, Mark Newton wrote:
>
> On 23/03/2010, at 3:43 PM, Owen DeLong wrote:
>>
>> With the smaller routing table afforded by IPv6, this will be less expensive. As a result, I suspect there will be more IPv6 small multihomers.
>> That's generally a good thing.
>
> Puzzled: How does the IPv6 routing table get smaller?
>
Compared to IPv4? Because we don't do slow start, so, major providers won't be
advertising 50-5,000 prefixes for a single autonomous system.
> There's currently social pressure against deaggregation, but given time
> why do you think the same drivers that lead to v4 deaggregation won't also
> lead to v6 deaggregation?
>
I think that the same drivers will apply, but, think of IPv6 as a Big 10->1
reset button on those drivers. Sure, in 30 years, we may be back to
a 300,000 prefix table, but, in 30 years, a 300,000 prefix table will be
well within the hardware capabilities instead of on the ragged edge
we face today.
> (small multihomers means more discontiguous blocks of PI space too, right?)
>
Yep. It does. However, IPv6 gives us a 30-50,000 prefix table now (when
we get there) and 10-30 years to solve either the TCAM scaling issue or
come up with a better routing paradigm.
I think that eventually an ID/Locator split paradigm will emerge that is
deployable. I think that SHIM6 and the others proposed so far are far
too complex and end-host dependent to ever be deployable.
Likely we will need to modify the packet header to be able to incorporate
a locator in the header in the DFZ and do some translation at the edge.
I haven't fully figured out the ideal solution, but, I think several others
are working on it, too.
Owen
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