DHCP6 Serves Prefix Outside the Interface's Prefix
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My DHCP6 server's "Primary Address Pool" defaults to being outside the prefix of the corresponding LAN interface.
I can find no mechanism by which to change that:
What am I missing?
I tried:- Changed the /56 prefix length to /60 and /64.
This updates the prefix length shown by the DHCP6 server, but has no influence on the numbers in the prefix. (I have a /48) - Change the value of the prefix using a different /56 subnet than the subnet ending in *:246:246. The DHCP6 prefix numbers do not change.
- Tried both the ISC and Kea servers.
- Performed countless reboots.
I also note that the string "246:240" is nowhere to be found in config.xml. Presumably because the DHCP6 server is supposed to obtain the prefix from the values entered for the Interface.
In case you are wondering why I set the LAN prefix to /56, I am planning to offer both individual IPv6 address out of that address space as well as /60s via prefix delegation. /56 was the next size up.
I am out of ideas what else to try. Suggestions are appreciated!
Thanks,- Lucky
- Changed the /56 prefix length to /60 and /64.
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@shamrock for starters why would you ever put a /56 on an interface? /64 is the only thing that should be on an interface. Maybe a /128 in some circumstances.. But an interface on a device/router/firewall etc.. should and would only be /64
You can use other larger prefixes in say a firewall rule or route.. Or a delegation to some downstream device that will break up that larger prefix..
2nd - that is the correct /56.. it would run from..
fd00:fd00:246:200:: - fd00:fd00:246:2ff:fff:ffff:ffff:ffff
A prefix is going to start on specific net break, if you put an address that is in the middle of the network, that doesn't change the network address.
Its easier to read with IPv4 as example..
Lets say you are using a 192.168.0.0/22
This range is 192.168.0.0- 192.168.3.255
If You put an address of say 192.168.2.1/22 on your interface.. The network that is on is still 192.168.0.0- 192.168.3.255
If you used 192.168.1.1, or 192.168.1.254 or 192.168.3.254 or 192.168.2.27, etc.. the network is still that 192.168.0/22 that runs from 192.168.0.0 to 192.168.3.255, does not matter where in that space the address you put on the interface lands.
A prefix or netblock/network is always going to start and end at specific addresses.. Just because you put an IP that is in that range on the interface, doesn't change the the network boundaries
If you wanted to use 246:246, that would be like the 71st subnet out of your /56
fd00:fd00:246:246::/64
fd00:fd00:246:246:0000:0000:0000:0000-fd00:fd00:246:246:ffff:ffff:ffff:ffff
