v6 subnet size for DSL & leased line customers

Wed Jan 2 23:09:41 UTC 2008

On 2 jan 2008, at 22:34, Joe Abley wrote:

> The community who would like the knob not to be "deaggregate" are  
> the same ones that are doing the deaggregation, which I think is as  
> it should be from a macro level

More precise: the two sets of people are part of the same community.  
I'm not sure if there's much overlap between the really bad  
deaggregators and those who are strongly pro-knob, though.

> As to "there must be better knobs" I think it may be a little late  
> for that; by design (or as a consequence of it) the set of IPv6  
> knobs is the same as the set of IPv4 knobs.

The trouble is that BGP doesn't have a meaningful inter-AS metric.  
(Although there is something that is called that.) If I want to  
increase my path length by 10% through a certain neighboring AS, I  
don't get to do that. I only get to double or triple it. (Unless I was  
doing very heavy prepending to begin with.)

This is easy to fix by adding a new metric to BGP that is increased by  
10 or 100 or 1000 at each hop by default, but which can also be  
increased by a larger or smaller amount as desired. In essence, this  
would make the AS path a lot more granular. Obviously this only works  
if a fairly large set of ASes implements this.

However, word on the street is that in order to get a new BGP  
attribute defined in the IETF idr wg, you need assurances up front  
that people are actually going to implement and use that new attribute.