[Kea-users] KEA DHCPv6 subnet prefixes from upstream IA_PD

[Owen DeLong]

Thanks. Bringing this back to the list for broader consideration...

I haven’t had a chance to experiment with this yet (other things overwhelmed the project in question), but am now coming back to it and have a few other high priority projects which require this functionality.

I found Issue 856 here:
https://gitlab.isc.org/isc-projects/kea/-/issues/856

Which requests a very similar capability. I’ve added an extensive comment to that issue because I think it got under-rated and the focus drifted towards the IA_PD client side rather than the subsequent distribution of IA_NA information based on the received IA_PD that the OP was seeking.

The more I look at SMB and Enterprise IPv6 implementations, especially ones where the upstream ISP is trying to use DHCP-PD to assign addresses to the downstream customer, the more I’m thinking that some form of functionality like this will be vital to making this practical.

Your assistance is much appreciated, I’ll let you know if I’m able to have any success with your solution. The key question is whether include interpolation will occur within a quoted string. I’ve never tried that before.

Thanks,

Owen


> On Jan 15, 2025, at 12:04, Darren Ankney <darren.ankney at gmail.com> wrote:
> 
> Hi Owen,
> 
> I'm afraid I don't have much experience actually using the mechanism.
> In your proposed suggestion, I think it would look like this:
> 
> “prefix”: "<?include “prefix_file”?>1:/64” {
> 
> and the contents of prefix_file would be:
> 
> 2001:db8:f342:384
> 
> with no new line character or spaces.  Would that work?  I don't know.
> Perhaps you could test in a lab setting before implementation?
> 
> Thank you,
> Darren Ankney
> 
> On Wed, Jan 15, 2025 at 7:40 AM Owen DeLong <owen at delong.com> wrote:
>> 
>> Can I really substitute part of a string from an include file? Forgive my ignorance, but what would the syntax for that look like?
>> 
>> Imagine: prefix in file is “2001:db8:f342:384” an example representing a /60 typically issued by a certain address stingy cable provider.
>> 
>> Statement needed in kea:
>>       “prefix”: “2001:db8:f342:3841::/64” {
>> 
>> Ignoring for the moment, the need to include said prefix fragment in 16x3 places (subnet declaration, pool start, pool end, plus in each reservation), I’m trying to figure out how even this one statement would look:
>> 
>>        “prefix”: <include “prefix_file”>”1:/64” {
>> 
>> Seems unlikely to parse. Can I make a call to concat() in that context and use the include directive as one of its arguments?
>> 
>> I’m not trying to be obtuse, just trying to figure out a practical implementation of your suggestion.
>> 
>> Owen
[snip]

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