ISP DHCPv6 and /48

Baldur Norddahl baldur.norddahl at gmail.com
Fri Jul 10 09:26:32 UTC 2015


Hello,

Let me introduce another first world problem. We use DHCPv4 to assign each
user a IPv4 /32 and DHCPv6-PD to assign a IPv6 /128 WAN plus a /48 prefix.
All good.

However we are an ISP where the customer chooses his own CPE. We just ship
a modem/mediaconverter/ONU with one ethernet port. The customer is expected
to plug his home router in here.

However sometimes we have a customer that wants to buy an extra IPv4
address. We are happy to sell him that. Now he has two (or more) IPv4
addresses. Turns out most of these customers are not configuring the extra
IPv4 addresses on a single home router (most CPEs probably can not handle
multiple WAN addresses anyway). Instead these people put in a switch and
then have multiple devices, each with one IPv4.

A typical setup is a home router (CPE) plus a server, or they might have
some VPN device forced on them by their employeers or they might simply be
sharing the internet connection with the neighbour (we allow that).

However we are forbidden to deliver more than one /48. What to do?

Currently we will deliver exactly one /48 to one device and just say sorry,
you will have to figure out how to get IPv6 on your other devices. The
experience is that 100% of the guys then simply do not have any IPv6 on the
other devices. Figuring out how to route a slice of that /48 is too much
for even most technical minded customers.

Would you deliver say /52 prefixes instead but reserve /48, so the DHCP
server has the option to deliver up to 16x /52 per customer?

Regards,

Baldur



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