[proactivesvcs]

As I understand it, there have been a few nation-scale Internet outages that have been a result of IPv4 address tables reaching their resource ceiling (not relating to NAT) - another example of how IPv4 is no longer fit for purpose regarding hardware resources.

[mprovost]

Those were caused because Cisco by default (optimistically) partitioned a big chunk of the routing table memory for v6 routes. The fix was to reduce the memory usage for v6 and give that memory back for v4 routes. So really it was allocating so much space for v6 before there was any need that caused those outages.

[tptacek]

If 32 bit address tables are reaching capacity, increasing the size of the address space is unlikely to resolve the problem.

[mikecb]

Doesn't ipv6 include efficiencies for this, like hierarchical prefixes?

[tptacek]

In practical reality, doesn't that just mitigate the strain caused by an explosion in the size of the address tables?

[toast0]

A sometimes large but solvable part of the problem in ipv4 routing table sizes is numerically adjacent routes that could be aggregated into fewer announcements but aren't; ipv6 doesn't help with that. Another part of the problem is that many networks have lots of allocations that aren't adjacent, so they can't aggregate them; ipv6 should help with that as there's room for big allocations.

[mikecb]

I guess it depends on how big the efficiency gain is, but afaik it's pretty big.