It's Ars Tech's turn to bang the IPv4 exhaustion drum

Mikael Abrahamsson swmike at
Mon Aug 18 13:57:27 CDT 2008

On Mon, 18 Aug 2008, Deepak Jain wrote:

> operational content: Is anyone significantly redesigning the way they 
> route/etc to take advantage of any hooks that IPv6 provides-for (even if its 
> a proprietary implementation)? As far as I can tell, most people are just 
> implementing it as IPv4 with a lot of bits (i.e. /126s for link interfaces, 
> etc).

Yes, there are those of us who want to save number of routes and 
"spending" IPv6 addresses to save on TCAM and convergence time.

Using /112 for link networks to make the last octet ::1 and ::2 for links 
also makes sense from the human perspective.

Also, I try to involve myself in IETF ipv6ops-wg via their mailing list, 
and they're definitely interested in getting more people involved. Doing 
IPv6 in the core is easy, it's in the access that there is much work to be 
done for all access methods. If you're doing PPPoE you're probably home 
free, most of the rest just isn't operationally sane yet for ISP 
environment (stop customers doing rouge RA, man in the middle, spoofing).

For instance, I (and a few others) have been advocating that ISP core IPv6 
space and customer IPv6 space should be separate, with link-local in 
between (so core can be "protected" at borders, and also to save on TCAM 
in the access devices (doing routing+antispoofing if there is only single 
/48 to the customer uses less router resources than doing /48 + link 
network)). Other people have other opinions.

A lot of this is happening now, so if you want something down the road, 
please put in the effort now.

Mikael Abrahamsson    email: swmike at

More information about the NANOG mailing list