v6 & DSL / Cable modems [was: Private use of non-RFC1918 IP space (IPv6-MW)]

TJ trejrco at gmail.com
Thu Feb 5 01:56:42 UTC 2009

>Let's face it - the current v6 assignment rules are to solve a 1990s set
>of problems.  

Perhaps, time moves ever forward.  

>A /64 isn't needed now that we have DHCP(v6).   Setting
>the idea in people's heads that a /64 IS going to be their own statically
>insane and will blow out provider's own routing tables more than is
>rational. (Think of the processing overhead of all the DSL/Cable customers
>going up and down).  This is going to be far more of an issue and drive
>network design than a minor blow out in the v6 routing table.

However, many do not "have" DHCPv6 ... WinXP, MacOS, etc. are not capable.
Also - does DHCPv6 currently have an option for prefix length?  Just asking.

WRT /64s (or really, /56s and /48s being assigned to clients) - note that
these are NOT static assignments permanently belonging to the client.  They
are hopefully dynamic, hopefully via DHCPv6-PD (hopefully
available/supported by then) ... similar to the single public IPv4 address
most of us dynamically get @home today.  

AND, how does having a route for a /56 impact my routing table more than
having a route for a /xx (something longer)??
It does mean the ISP needs a larger initial allocation, but still just one
route ... 


More information about the NANOG mailing list