OpenWrt/LEDE Project

  • Status Unconfirmed
  • Percent Complete
  • Task Type Bug Report
  • Category Base system
  • Assigned To No-one
  • Operating System All
  • Severity Medium
  • Priority Very Low
  • Reported Version All
  • Due in Version Undecided
  • Due Date Undecided
  • Private
Attached to Project: OpenWrt/LEDE Project
Opened by Eric Luehrsen - 04.02.2017

FS#461 - Mass Cascade of DHCP ULA Prefix Assignments with DHCP-PD

Here is one that gets a bit ugly. Lets say we chain a bunch of LEDE based routers together. Lets also enable a nice numbering system in IP4 and IP6. Lets enable DHCP-PD through the network, because our ISP was generous with a /56. The IP4 is only static and is easy to control, see table below. Its tedious, but easy. The problem is in parallel the IP6 addresses compound in the ULA region. Each router DHCP-PD the ULA above it, and gets its own ULA from Global settings in Network UCI. There seems no easy way to control this mass cascade of ULA, and get good fail over.

Ideal Requirements:
(1) If router above is unavailable, then next tier router uses ULA (network global UCI) to begin assigning addresses to clients and subnets.
(2) If router above is available, then next tier router expires its self-generated ULA and subnets, and gets ULA from delegation above to then re-delegate to subnets.
(*) Bonus: make some parts optional

IP4 WAN Name Serves Subnet
(NAT) Router-1 Router-2A Router-3A Router-3B Router-2B

IP6 Roots Name Serves Subnet Delegates Subnet
2001:db8/56 Router-1 2001:db8::1/64 2001:db8:0:10/60
fd00:ac10/48 fd00:ac10::1/64 2001:db8:0:20/60


2001:db8:0:10/60 Router-2A 2001:db8:0:10::1/64 2001:db8:0:14/62
fd00:ac10:0:10/60 fd00:ac10:0:10::1/64 2001:db8:0:18/62
fd00:ac11/48 fd00:ac11::1/64 fd00:ac10:0:14/62


* please, i don’t want to type more. see how the ULA prefixes just keep multiplying.
** ‘172.16’ = ‘ac10’

Eric Luehrsen commented on 04.02.2017 06:09

... and flyspray just reformatted my table into garbage. ~~fantastic~~ :-/

Dave Täht commented on 04.02.2017 21:45

This is no doubt related to the other issues I'd had with dhcp-pd....

I gave up on pd entirely for now.

Christopher Friedt commented on 04.04.2017 23:00

Ahh... so it isn't just me.

I've come to believe that my ULA ip's are not getting assigned correctly on my subnet because of dhcpv6-pd.

E.g. On one client, I expect to have / fd27:fcc0:fa2a::c

but the host is getting assigned / fd27:fcc0:fa2a:10bc:c89e:b72b:f675

Dnsmasq actually resolves properly to fd27:fcc0:fa2a::c which is both reassuring and frustrating.

Even having a bit of information about the best way to debug the "automagically" generated init scripts / lua code (for luci) would be nice.


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