If you can't hang 4k customers off a switch, why does IPv6 need so many bits for the host portion?
Matthew Kaufman (Sent from my iPhone) > On Sep 8, 2015, at 12:54 PM, valdis.kletni...@vt.edu wrote: > > On Tue, 08 Sep 2015 19:40:44 -0000, Josh Moore said: > >> The question becomes manageability. Unique VLAN per customer is not always >> scalable. For example, only ~4000 VLAN tags. What happens when you have more >> than that many customers? > > If you're hanging 4K customers off the same switch, you probably have bigger > issues than running out of VLAN tags... > >> We are talking very, very, small customers here. SOHO to say the most. >> /64 should be more than sufficient for their CPE router. > > A Linksys WNDR3800 running CeroWRT (and probably OpenWRT by now) will prefer > to > create multiple /64's - one for the 4 wired ports, one for private access on > the > 2.4G radio, one for guest access on the 2.4, and another private/guest pair > on the 5G radio. So there is CPE gear out there now that can blow through 5 > /64s > by default, and more if you enable VLANs. > > A /56 allocated via DHCPv6-PD would be a *minimum*. And prefixes are cheap, > so you may as well hand them a /48, just in case they have a second WNDR3800 > at the other end of the building for coverage - because that one will then ask > the upstream one for a -PD allocation. So if you give the CPE a /48, it can > keep a /56 for itself, and hand the downstream a /56, and they can each > allocate /64s as needed. > > And remember - prefixes are cheap and plentiful, so don't bother with /52 > or /60, just split on 8-bit boundaries to make life easier for yourself... >