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c001bea7ec40
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IPv6 DHCP and ULA and GUA

Thu Jan 13, 2022 12:36 pm

Help Needed...
Received my first Mikrotik, a hEX S, and testing if will suit my needs as an edge router for a small business network.
I want to deploy IPv6 a specific way, and I have it working for an openwrt config, but would like to give the Mikrotik a try.

Since by design, hosts can have multiple IPv6 addresses, I use both ULA's in the LAN, as well as GUA from the ISP. This has added reliability and resiliency to the network when the ISP 'needs' to change prefixes, or some odd thing happens with GUA prefixes. I have the internal ULA's to use for internal DNS and internal services, and use the GUA for external transits.

So at the Mikrotik, I want to setup a ULA pool that i can DHCP to the hosts. I dont want (prefer not) to use the EUI-64 (SLAAC) as the 'assigned' host address.
The GUA prefix can transit to the hosts, but would also like to have DHCP for some hosts that offer external services.

Thus a host will receive a GUA prefix, and a ULA prefix and/or ULA assigned address. I have used host 'tokens', but not preferred.
-- ISP Prefix (::/56) --dhcpv6--> [Router] --nd-ra(GUA)--> {Host: SLAAC: ISP prefix: EUI-64 + privacy addresses}
[Router] --dhcpv6(GUA)--> {Host: ISP prefix: assigned address}
[Router] --dhcpv6(ULA)--> {Host: ULA prefix: assigned address}

Is this possible on RouterOS 6.49?
I think this should be doable, but not able to configure it seems?
 
proximus
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Re: IPv6 DHCP and ULA and GUA

Thu Jan 13, 2022 6:41 pm

So at the Mikrotik, I want to setup a ULA pool that i can DHCP to the hosts. I dont want (prefer not) to use the EUI-6 (SLAAC) as the 'assigned' host address.
The GUA prefix can transit to the hosts, but would also like to have DHCP for some hosts that offer external services.
.
RouterOS DHCPv6 server can only delegate IPv6 prefixes, not addresses.
https://help.mikrotik.com/docs/display/ROS/DHCP+Server

This is an unfortunate limitation in ROS.
 
c001bea7ec40
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Re: IPv6 DHCP and ULA and GUA

Fri Jan 14, 2022 9:48 am

RouterOS DHCPv6 server can only delegate IPv6 prefixes, not addresses.
!Wow, for the feature set that seems to be in the Mikrotik, this is definitely an odd shortcoming, and not giving a network architect the freedom to choose how to deploy IPv6. This only makes sense if all this router's IPv6 'host's are themselves routers, or SLAAC only hosts (or if hosts take a prefix?)

So can only get what I want if I deploy a 'proper' DHCPv6 server downstream the Mikrotik?
@Mikrotik, please explain if I am missing an important "why" here, or still a work in progress?

Kind of disappointed I took the time to learn the Mikrotik, as I was enjoying the clean config tooling.
With OpenWRT, you can install or script a workaround... is there something like hooks that may be scripted to extend to my use case?
 
Sob
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Re: IPv6 DHCP and ULA and GUA

Fri Jan 14, 2022 2:56 pm

The "why" is simple (I guess), there's so many things to do, and they didn't get to this one yet. It will happen... eventually.
 
c001bea7ec40
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Re: IPv6 DHCP and ULA and GUA

Sun Jan 16, 2022 9:34 am

I guess, it depends on what base of customers Mikrotik wish to support, and what market tier they are targeting, for which sections are a priority.
(Of course) My preference is for them to support my 'wants'.
I see trekking through some of the net, that improving the IPv6 stack has been requested for a few years now, and specifically for the DHCPv6 functionality.

I would argue that my cohort or tier of user / admin, for small and medium business network infrastructure, would fully welcome and be quite loyal to a stable core like the Mikrotik routers could provide, if base functionality like the IPv6 stack supported their needs.
Having this lack for me, and seeing the arguments, that SLAAC is 'good enough' for deployment in the LAN, so eventually this _may_ be updated, eventually. I am not against opinionated design, I just didn't think to expect it in a standards based protocol hardware.

This does seem to put me on the fence, and to what other gotcha's I would run up against if I deployed the Mikrotik.

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