Do I have a /56 or /60

rkcin

My WAN is configured for DHCPv6 with a delegation size of 60 with "send prefix hint" selected. I have two internal subnets which track the WAN and each get their own IPv6 prefix. I expected them to get their own prefixes on the same /60. But, the only thing they each have in common is the first 56 bits. Does this mean I have a /56 subnet from my provider? If I switch the WAN desired delegation size to 56 I get no IP6 previx on the tracking interfaces. I'm confused by the selection of the desired delegation size. What does it do exactly and why doesn't it represent what I get?

LAN1: 2601:2:4e88:ee0:
LAN2: 2601:2:4e88:ee1:

Did I count the bits correctly?

priller

Your /60 prefix should be ~~2601:2:4e88:ee8::~~ 2601:2:4e88:ee0::

You can view that here: /var/dhcpd/etc/dhcpdv6.conf

Take that prefix and plug it in here: http://www.gestioip.net/cgi-bin/subnet_calculator.cgi

Making the available /64's:

2601:2:4e88:ee0::/64
2601:2:4e88:ee1::/64
2601:2:4e88:ee2::/64
… etc

If you are Comcast residential, requesting a /56 will get you nothing.

razzfazz

@priller:

Your /60 prefix should be 2601:2:4e88:ee8::

I believe that should be 2601:2:4e88:ee0::, no?

razzfazz

@rkcin:

LAN1: 2601:2:4e88:ee0:
LAN2: 2601:2:4e88:ee1:

Note that the numbers within each group are "right-aligned." I.e., these prefixes are exactly the same as the following:


LAN1: 2601:0002:4e88:0ee0::
LAN2: 2601:0002:4e88:0ee1::
      ^^^^ ^^^^ ^^^^ ^^^

Each digit represents four bits; if you compare the two prefixes, you'll see that their leftmost 15 digits match, so they're in the same /60.

priller

@razzfazz:

@priller:

Your /60 prefix should be 2601:2:4e88:ee8::

I believe that should be 2601:2:4e88:ee0::, no?

Agh! Thx

rkcin

Yes, thank you. That's where I went wrong. I see it now.