[Cerowrt-devel] ipv6 confusion with source specific gateways.

[Dave Taht]

On Wed, Nov 26, 2014 at 7:21 PM, Chuck Anderson <cra at wpi.edu> wrote:
> On Tue, Nov 25, 2014 at 11:11:17PM -0800, Dave Taht wrote:
>> Some days I just lose it with prefix math. Or maybe we have a bug.
>
> Prefix math, there is no bug.
>
>> So here is a default gateway. So far as I know it is getting a /56
>> actually, not a /60, but it is requesting a /60 and thus distributing
>> a source specific route to that /60.
>
> Looks like a /60.
>
>> default from :: via fe80::201:5cff:ee62:b646 dev ge00  proto static  metric 1024
>> # should I even have a default route at all?
>> default from 2001:558:6045:e9:44a9:4a25:ece9:55c3 via
>> fe80::201:5cff:ee62:b646 dev ge00  proto static  metric 1024
>> # my uplink, looks sane
>>
>> default from 2601:c:ce00:9d0::/60 via fe80::201:5cff:ee62:b646 dev
>> ge00  proto static  metric 1024
>> # and see that /60...
>>
>> # and then there is the default ipv6 address assignements on cero.
>>
>> 2601:c:ce00:9d1::/64 dev gw10  proto kernel  metric 256  expires 326362sec
>>
>> Now, where my brain crashes: shouldn't 2601:c:ce00:9d1::/64 actually
>> be something like
>>
>> 2601:c:ce00:9d01::/64 not, 2601:c:ce00:9d1::/64?
>
> No, it is correct.  The /60 is:
>
> 2601:c:ce00:9d0::/60
>
> which is really this when expanded out (zero-pad each : section):
>
> 2601:000c:ce00:09d0::/60

You are absolutely correct. Thank you!

>
>
> Now the 60 bit prefix is:
>
> 2601:000c:ce00:09dX:XXXX:XXXX:XXXX:XXXX
>
> where X is the part which can be assigned to your LANs.  The first X
> is a 4-bit nibble that was assigned "1" by Cero creating a /64 subnet
> prefix, leaving the remaining 64 bits for your Interface IDs...

It turned out that I had a non-source-specific babeld between me and
it, also (bloody meshy routing!),
which was messing things up. Worse, that is on a roof where I cant
update it easily.

Also I AM getting a /56 from a comcast business class account
elsewhere on the net...

but grokking hnetd is killing me.

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-- 
Dave Täht

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