[ipv6-wg at ripe.net] RE: [6bone] /20 allocated - update your BGP filters!

On 11-mei-04, at 12:17, amar wrote:

>> Still, a /20 allows for 268435456 /48s. Is Telia really going to give
>> half of the inhabitants of Europe a /48?

> I fully understand Your point of view.

No point of view, just asking.

>    P   48-P Total/48s    Threshold Util%
>    -------------------------------------
>    20  28   268435456    5534417   2.1%

> It is all based on RFC3194. Do You suggest that the
> HD-Ratio in RFC3194 should be changed?

The HD ratio is based on assumptions. We should base our policies on 
fact.

The trouble with the HD ratio is that it assumes that one out of every 
five digits is lost due to aggregation boundaries. That assumption may 
hold occasionally, but it certainly won't as a general rule. This is 
especially true in IPv6, where the address length is very long. With 45 
bits between the 2000::/3 and the subnet edge that's 9 bits that are 
lost. I think that's excessive.

See http://www.bgpexpert.com/archive2003q3.php#12 (at the bottom) for 
some additional text on this.

Now I don't have a very good idea about realistic aggregation levels in 
very large IPv6 ISP networks. If you can shed some light on this, that 
would be very useful.