[Starlink] dhcpv6-pd details

[Dave Taht]

On Mon, May 17, 2021 at 12:04 PM Nick Buraglio <nick at buraglio.com> wrote:
>
> As discussed privately with Dave, I have removed the starlink provided
> router and replaced it with a Mikrotik RB2011 to allow for more

Running routerOS? Latest beta's of that have cake in 'em.

> granular control, and to better tie into my existing network.

Starlink provides a router, also? I'm so confused. I thought the dishy
was all there was. Care to tear it apart and describe what's in it?

> This has
> allowed me to make a dhcpv6-pd request that is reasonably stable (so
> far it has changed once in the last 2 months). The lease time is
> incredibly short, which is a little strange but as long as the DHCPv6
> server is the same and remains unchanged, it should just hand out the
> same prefix upon request.

That was a terrible habit that comcast had got into in the early days
that forced
openwrt to flush and reload the firewall every minute, or less.

I'd pioneered a stateless firewall in cerowrt that never ever ever
needed to reload the
rules, using a pattern match for each specifically renamed ethernet interface.

Regrettably that was not accepted into openwrt, because "nftables" was
just around the corner.
It scaled beautifully to tons of interfaces going up and down so long
as they were named appropriately,
at far less cpu overhead for complicated rules than the standard
openwrt firewall.

https://www.bufferbloat.net/projects/cerowrt/wiki/CeroWall/?version=9

Anyway, I don't remember all that we did to suppress the flood of
useless static changes
to everything ipv6, but I hope that whatever we ended up doing still
works in this case.

> I also built a very crude measurement display that just uses curl get
> and dig via smokeping to display reasonable RTT. It's detailed in the
> reddit post here:
> https://www.reddit.com/r/Starlink/comments/mykxjv/functional_ipv6_and_some_crude_starlink_latency/
> and can be viewed directly here:
> https://starmon.qosbox.com/

THX! We really need to collect the "good" information and publish it
somewhere, the reddit noise level is too high.

One piece of mis-information I think was the news you can "route"
packets over ipv4 with a box in front of it and
a default gw of 192.168.100.1 Not clear from that news whether or not
NAT was required on the next hop or not... ?

(that's from another reddit post I mis-remember)

>
> Making dhcpv6-pd work is pretty standard:
>
> /ipv6 dhcp-client
>
> add add-default-route=yes interface=ether2 pool-name=starlink-ipv6
> prefix-hint=::/56 request=prefix
>
> On each interface you want to have IPv6 on:
>
> /ipv6 address
>
> add address=::1 from-pool=starlink-ipv6 interface=bridge.8
>
> add address=::1 from-pool=starlink-ipv6 interface=bridge.6

THANKS SO MUCH. I am thinking at the moment that openwrt's dhcp-pd
implementation is currently
broken (it's not working on admittedly a comcast modem I just got that
I'd not used before), but
as soon as I get a chance I'll try configuring odhcpd6 to do something
like this. If I can remember how.


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> Starlink at lists.bufferbloat.net
> https://lists.bufferbloat.net/listinfo/starlink



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Dave Täht CTO, TekLibre, LLC