IPv6 over Starlink

pst · Apr 17, 2024, 8:12 PM

My DHCPv6 config screen doesn't show the actual delegated /64 like yours (and others) show - but instead just "WAN1_STARLINK/0/64"

I had the same problem once after adding a new LAN with IPv6 tracking the WAN. It was solved by doing a Release / Renew on the WAN interface (under Status / Interfaces). Once the WAN had reconnected the DHCPv6 config screen showed the correct prefix.

mystic330 · Apr 18, 2024, 4:19 AM

It’s gone from bad to worse now…
I hit release /renew on the WAN, gave it several mins and neither v6 or v4 worked - got no addresses on either. I was hard down.
I had to reboot the Starlink router - once it came back I have v4 connectivity but I’m still not getting any v6 address - routable or link-local…
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I don’t think this v6 code is ready for prime time

mystic330 · Apr 18, 2024, 4:26 AM

The log indicates a “ transmit failed: Can't assign requested address”
Is there some cache that needs to be cleared?

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Gertjan · Apr 18, 2024, 7:32 AM

@mystic330 said in IPv6 over Starlink:

It’s gone from bad to worse now…
I hit release /renew on the WAN, gave it several mins and neither v6 or v4 worked - got no addresses on either. I was hard down.
I had to reboot the Starlink router - once it came back I have v4 connectivity but I’m still not getting any v6 address - routable or link-local…

The two are not related.
The dhcpc (IPv4 !) will emit a request for IPv4lease - you can see this happening in the DHCP log, just locate (Ctrl-F) all the lines with the 'dhcpc' lines.
If there is no answer from the upstream dhcp IPv4 server .... well ... that's an issue on its own. If you need to reboot the upstream starlink stuff, that's pretty lame.
To get more info : use the search button at the top, enter 'Starlink' and you'll find many posts about startlink and WAN issues.

This :

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and the absence of log lines from dhcp6c (the DHCP client IPv6 process) where you can see (see my example) that the dhcp6c is asking for a lease, and get one (one at lease) means that

you get an IPv6 address for your LAN :

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Btw : this option is somewhat strange :

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You don't want just prefix(es), you want also an IPv6 address for your WAN .... right ( ? )

Try this : Hook up on the starlink router another device, like a PC.
When connected : check the starlink router GUI for Ipv6 leases it handed over, or type

ipconfig /all

on your PC.
Did it get an IPv6 like 2605:59c8:5200;bbb0:a.b.c.d ?

If so, the DHCP6 starlink server (in your router, or further upstream) hands over IPv6 addresses, but ...
no prefixes ?

The thing is, your pfSense is not a normal end device like a PC, its a router.
It needs a IPv6 for it's WAN needs, like a PC.
But it has also, on the other side, a LAN interface, and on this interface you can connect many devices.
Hence the need of a 'pool' of IPv6 addresses that it, pfSense, can hand over to these end user devices, exactly like the upstream router to which pfSense is connected.
These 'pools' are the prefixes. One is needed per pfSense LAN.
If Starlink doesn't give you a prefix, pfSense can't hand over IPv6 lease on the LAN side, as it has no FHCPv6 pool to do so.

Again : this means :

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that pfSense did not obtain a prefix for that LAN.

It is very possible that the starlink router can only give IPv6 addresses for devices connected, like PCs, phones etc.
But if it does not support to 'lease' IPv6 prefixes : this means you can't use a down stream router like pfSense, and propagate IPv6 addresses on its LAN.

mystic330 · Apr 18, 2024, 1:52 PM

They are related in that I had both v4 and v6 addresses on my WAN interface - just delegation wasn’t working - and I clicked “release” based on a suggestion here, and both v4 and v6 DHCP stopped working altogether.
I not worried about the v4 issue - just found it odd - this is a v6 troubleshooting thread and I’m specifically looking at/posting logs from the “dhcp6c” processes and help on how to troubleshoot v6 on pfsense. I’m way beyond the router vs end-node, ip addressing, etc stage (CCIE for 15 years)

I was previously getting a v6 address on my WAN interface, so I know Starlink is handing out/supports DHCPv6 and I was also getting a gateway so I know RA was working. (Now I need to troubleshoot why it suddenly stopped)
(I didn't realize the Only send prefix checkbox was checked - as I was trying different options it must've gotten checked - Thanks, I'll uncheck that).

What wasn’t working is delegation of a /56 from Starlink and the first /64 (with ID 0) to my LAN interface. My LAN interface never reported a routable v6 address (which I believe is keeping my dhcpv6 server on the LAN interface from working). For those of you that have v6 delegation working from your ISP, do you have a routable v6 address from the delegated block assigned to your LAN interface?? I know this is not required as a link-local address as the gateway on the LAN will allow routing to work, but I never see any dhcpv6 leases being handed out and I believe not having a v6 address on the LAN interface is the reason….

mystic330 · Apr 18, 2024, 2:18 PM

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This is from starlink's web site. They claim they delegate a /56.

mystic330 · Apr 18, 2024, 2:44 PM

OK - When in doubt - REBOOT!

With all the standard v6 settings as shown in other posts, a reboot brought everything into a working as expected state!

I have a routable v6 address on my LAN interface:
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...which allows the DHCPv6 server to work on the LAN interface as I now have v6 leases showing:
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Here's my config for others to reference:

WAN interface - v6 address set to DHCPv6
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LAN interface - v6 address set to "Track interface":
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...with the track interface set to the WAN interface getting the v6 delegation and the prefix ID set (0 in this case refers to the first /64 within the delegation (/56 in the case of Starlink):
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Then enable DHCPv6 server on the LAN interface:
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Thanks for everybody's help!

Gertjan · Apr 18, 2024, 3:55 PM

@mystic330

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256 prefixes available

32 of these ....

timg_11 · Oct 19, 2024, 3:55 PM

@Gertjan Hi I just joined this forum for this thread.
After registering and logging in all of the images of screen captures are showing as "UUID-string.png" clicking on them displays "Not Found".

What do I need to do to see the embedded images?

bmeeks · Oct 19, 2024, 5:43 PM

@timg_11 said in IPv6 over Starlink:

@Gertjan Hi I just joined this forum for this thread.
After registering and logging in all of the images of screen captures are showing as "UUID-string.png" clicking on them displays "Not Found".

What do I need to do to see the embedded images?

A few months ago the forum software experienced a serious crash and many links to images in posts were irreparably broken. Unfortunately, the links you seek were among those broken.

JKnott · Oct 19, 2024, 9:49 PM

@mystic330 said in IPv6 over Starlink:

It seems like I'm getting delegated /64s through DHCPv6 (LAN hosts are getting non local-link addresses)

Does Starlink provide a prefix through DHCPv6-PD? Or just the one /64? My cell phone does the latter.

adaviel · Mar 10, 2025, 6:28 AM

@timg_11 The images are available on the Wayback machine at archive.org.
I just did the same thing as you, but I'm trying to route IPv6 on Linux