Filtering prefixes longer than /24

[itojun@iijlab.net]

>The scaling of IPv6 wrt. routing table size is IMO a big non-issue; a
>remnant from the '95 when people started to get worried about the growth
>of DFZ.
>
>Nowadays 100,000 routes is no big deal.  Any "core" router which should be
>able to get full internet table can deal with this without problems.  You
>shouldn't be participating with your old 4500 Cisco with 16 MB of memory.
>Thus, I don't see what's the point of trying to minimize the size with all
>costs.

	two comments:
	- core routers need to carry both IPv4 full routing table and IPv6
	  full routing table, until we phase out IPv4.
	  (or you need to babysit separate routers, separate fibers...)
	- routing table in IPv6 will eat 4 times more memory than IPv4
	  if the # of entries is the same.
	so I believe it is not a "non-issue" (or it is safer to think that way).

	does anyone have performance measurement/whatever with big big big
	IPv6 routing table installed onto a router?  what is the routing table
	size vendors use for toture-test?

>Currently, the effectively changing IPv6 prefix size is smaller than with
>IPv4, and the population of it going to be sparser.  Also remember a big
>problem of current IPv4 routing table size are small advertisements,
>like /24 and /23 -- with IPv6 these are all within one /48, and are thus
>automatically very effectively aggregated.

	we can *potentially* have a lot of routes if you advertise /48 to
	worldwide.  compare 2^(48-16) and 2^(24-8).

itojun