IPv6 - real vs theoretical problems

Mikael Abrahamsson swmike at swm.pp.se
Fri Jan 7 14:39:35 CST 2011

On Fri, 7 Jan 2011, Deepak Jain wrote:

> least technical user base. (side note, if I were a residential ISP I'd 
> configure a /64 to my highly-controlled CPE router and issue /128s to 
> each and every device that plugged in on the customer site, and only one 
> per MAC and have a remotely configurable limit of say 50 devices or 
> whatever the mac table limit was. So I only have one route entry in my 
> aggregation layer and if the customer blows his CPE router up, I'm still 
> protected.)

This is exactly the reason to issue /48 or /56 to the end user. You give 
them plenty of space, and you then don't have to care anymore about what 
the user does with this space. You keep do LL only between CPE and PE, so 
you only need to keep 4 TCAM entries per customer (one for the /XX route, 
one for the LL adjacancy, one for the permit ACL to permit packets from 
the /XX, and one deny line. (I might be misunderstanding exactly what's 
needed here and a few TCAM entries more are needed, but you get the idea).

> until routers get smarter, I don't see how all that dead routable space 
> is a good thing.  Customers are paying for and getting a service, a 
> continuous relationship with some set of SPs. In that service they

If I give them a /56 then it's zero administration for me for the 
forseeable future. Why on earth would I want to handle customer 
administration when I don't need to?

Mikael Abrahamsson    email: swmike at swm.pp.se

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