dhcpcd-discuss

On 09/01/2018 03:37, John Roman wrote:
> Greetings,
>
> im trying to get  ipv6 to propagate from an x86 router ive configured to
> 2 interfaces.  So far on the router i have:
>
> interface eth2
>    ipv6rs                         # enable routing solicitation get the
>      ia_na 1                        # request an IPv6 address
>        ia_pd 2 eth2/0 eth1/1 eth0/2   # request a PD and assign it to
>        eth1
>
> this assigns a proper ipv6 to my uplink interface (eth2) during dhcp
> solicitation 2605:e000:9fc0:28:68d7:19f0:5ed0:a740
>
> this also assigns eth0 and eth1
> 2605:e000:130a:101:2000::1
> 2605:e000:130a:101:1000::1
>
> respectively, however from a desktop connected to 1000::1 I cant seem
> to get ipv6 traffic to flow properly...im not sure if my prefixes are
> correct?
>
> the desktop is 2605:e000:130a:a:1d7a:7b07:5fb:8d45 prefixlen 64
> however my router interface 1000::1 and 2000::1 are prefixlen 68...
>
> the desktop shows the following routes:
> 2605:e000:130a:a::/128         [::]                       Un   0   2
> 0 eth0
> 2605:e000:130a:a:1d7a:7b07:5fb:8d45/128 [::]                       Un
> 0   6    14 eth0
> 2605:e000:130a:a::/64

Yeah, that won't work - you can't fit a larger prefix into a smaller 
one. Using a /68 prefix on the router means you'll need a /69 or bigger 
prefix on the desktops which means you can't use SLAAC as that's only 
/64 so you'll need to use DHCPv6 instead.
If you don't want to do that (and that's also outside the scope of 
dhcpcd) then you need to request a smaller prefix delegation from your 
ISP. You need a /64 per downstream interface so you should be able to 
get that at a minimum, but that only means one downstream interface.
I would request a /56 or /60 like so:

interface eth2
  ipv6rs
  ia_na 1
  ia_pd 2/::/60 eth2/0 eth1/1 eth0/2


Roy