Re: Splitting /64 over Multiple Gateway Interfaces in rtadvd

On Thu, Mar 24, 2005 at 07:58:08PM +0000, Christian Weisgerber wrote:
| Ben Goren <[email protected]> wrote:
| 
| > That still leaves 281,474,976,710,656 /48s, assuming that's the only 
| > way you sliced it.
| > So, nowhere near as many /48s as I had thought, but still enough to not 
| > start worrying.
| 
| Indeed.
| 
| > But...that also means that each /48 comes with 2**80 addresses, no? 
| 
| Sort of.
| Ben, you really should have looked at an introduction to IPv6 before
| jumping into this thread.  Typically, an IPv6 unicast address breaks
| down like this:
| 
|     |        48 bits          |  16 bits  |       64 bits              |
|     +-------------------------+-----------+----------------------------+
|     | global routing prefix   | subnet ID |       interface ID         |
|     +-------------------------+-----------+----------------------------+

Global routing prefixes probably shouldn't exceed 32 bits, to avoid
issues like the huge routing tables we have now. With 48 (actually 45)
bits of routing prefix, there's 2**48 possible prefixes. That's quite
a few to put in your routers memory. (Although there currently are
only 3 /16's in use on the global internet, making for 3 times the
total address space of IPv4 in v6-prefixes - 12 billion
(12,884,901,888) routes.)

For naddy's prefix (2001:6f8:124a::/48), there's a /32 that has been
allocated to Easynet Group plc. So all traffic for 2001:6f8::/32 is
sent to Easynet who then splits off 2001:6f8:124a::/48 and routes that
over a tunnel to naddy, who in turn splits that up into (apparantly)
two /64's (leaving him 65,534 networks for later use).

I see mostly /32's and /35's on our routers. Some /24's and /28's for
6bone space (3ffe::/16). The smallest prefix we learn from a peer is a
/48, there are 16 of those and of those, most look (at first glance)
like they're not being aggregated properly.

I would still love to feed all those (v6) prefixes to OpenBGPD. Any
word on progress in that area ? Should I send some beer to Henning or
Claudio perhaps ? ;)

Cheers,

Paul 'WEiRD' de Weerd

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