Lit Fibre (UK) IPv6 stopped after powercut

F022Y

So for a long time my 1Gb/1Gb service with LitFibre has been working beautifully, today we had a powercut and after it came back IPv6 seems to be upset.

Now oddly the dassh looks fine and happy:-

But IPv6 was failing to resolve so i ran a test at test-ipv6.com and it says no.

Now here is where i'm assuming it's my config, I can ping ipv6 addresses via the WAN but not LAN (i used the forum URL but same with other addresses) but the config hasn't changed in months, the only change i can think of is that my ISP several weeks ago no longer required MAC spoofing for my static IPv4 address to work.

WAN to forums.netgate.com

LAN to forums.netgate.com

Doesn't really cause me any issues but a weird issue.

WAN page config

LAN page config

JKnott

@F022Y said in Lit Fibre (UK) IPv6 stopped after powercut:

I can ping ipv6 addresses via the WAN but not LAN

Run a packet capture and post the capture file here.

Gertjan

@F022Y

Several checks :
On your PC, where you exectued this :

ask if it has a IPv6 to work with :

ipconfig /all

I presume you use DHCPv6 to obtain an IPv6 lease.

You have a

On pfSense :
Your LAN DHCPv6 server obtained (by tracking) a prefix to work with :

You are using the DHCP "kea" or "ISC" ?
Switch to ISC ....

JKnott

@Gertjan

He said he gets a WAN address, but not LAN, so it's not a DNS issue. It's something to do with DHCP6, which is why I asked for the packet capture.

Gertjan

@JKnott said in Lit Fibre (UK) IPv6 stopped after powercut:

He said he gets a WAN address, but not LAN, so it's not a DNS issue.

DNS ? Did I mention DNS somewhere ?
It's a (I guess, details aren't shown) : "he did't get a prefix so the LAN DHCPv6 server can't work".
Wanted to see the LAN DHCPv6 server setup, if there was a 'valid' prefix showing, the first ('0' out of the avaible 'ffff'.

Or even the DHCPv6 WAN client detailed logs :

so prefix negotiation can be seen.

F022Y

Firstly thank you for the repies. So i am at a complete loss on this as I rebooted to do a packet capture and now IPv6 works like a charm.

But in case it helps i'll attach the pcaps etc.

packetcapture-igc0-20250316134737.pcap

I do have KEA for IPv4 addresses but not for IPv6 as that interface is set to track on the WAN.

As i say though after a boot she's happy again.

Thank you all again

JKnott

@F022Y said in Lit Fibre (UK) IPv6 stopped after powercut:

But in case it helps i'll attach the pcaps etc.

I see you didn't follow my directions. Instead of just the DHCP6 stuff, that file includes a lot of irrelevant stuff.

F022Y

@JKnott

Apologies i followed this:-

The pfsense box is down next to the ONT so by the time i got down and back up my PC had fallen asleep so assume UDP part was cleared

JKnott

@F022Y said in Lit Fibre (UK) IPv6 stopped after powercut:

Apologies i followed this:-

Including the instructions about the UDP port to filter on? By filtering on UDP port 546 or 547, doesn't matter which, you would have captured only the DHCPv6 packets.

Here's one I did a while ago. You'll see it contains only the 4 DHCPv6 packets and nothing else.

F022Y

So spoke to soon as it stopped again after scheduled maintence at 2am UTC today so ran through the advise you guys gave again.

Again after halting the system removing WAN cable booting up setting the following:-

Upon plugging the WAN cable back in IPv6 works again, as i'm in the middle of CDM upgrades on a rubrik cluster can't spend to much time poking.

Going to leave it overnight to check as another maintenance and see what happens.

@JKnott I know what i did wrong last time and will make sure not to repeat, now i assume the captured port is WAN? Just want to double check.

JKnott

@F022Y said in Lit Fibre (UK) IPv6 stopped after powercut:

I know what i did wrong last time and will make sure not to repeat, now i assume the captured port is WAN? Just want to double check.

Yes, that is correct. When you filter on those UDP ports, you will have 4 packets captured. You can look at the capture file with Wireshark, as I demonstrated with a screen capture.

Was that scheduled maintenance yours or your ISPs?

BTW, DHCP6 works exactly like DHCP4, with the solicit, advertise, request and reply packets. However, once that's completed, then the LAN prefix has to be obtained from the reply packet and applied to the LAN. There is nothing comparable to that in IPv4.

F022Y

It was ISP based, due to merging networks with their new owners CityFibre.

I do appreciate the assist.

F022Y

It died again, this time no IPv6 at all

packetcapture-igc0-20250318162548.pcap

JKnott

@F022Y said in Lit Fibre (UK) IPv6 stopped after powercut:

about 2 hours ago

It died again, this time no IPv6 at all

Here's what the reply packet shows:

The IA address should be the WAN interface address and the prefix address is your LAN prefix. Are you saying you're not seeing either of those? I also see you're getting a /48 prefix size. Nice you can get one that big. I only have a /56.

F022Y

Just logged back into pfsense after grabbing that pcap and the interface shows connections.

JKnott

@F022Y

Are you seeing the IPv6 pings leave your network? Perhaps there's a routing issue from your ISP. You can see the pings in packet capture, by filtering on ICMP6. You should see both the request and reply in the capture. What happens if you ping something closer than netgate? One thing you can do is traceroute to netgate or other and see how far it goes. Given the ISP is doing stuff, bad routes are a definite possibility.

You might also try this by tethering to a cell phone and seeing if you get the same results there. If the cell connection works, you can see if your pings can reach it from your Lit Fibre connection. You may want to use Wireshark on the computer tethered to the phone.

F022Y

Nope nothing.

packetcapture-igc0-20250318201715.pcap

Looks like my 3 cell connection doesn't support IPv6 so unable to test like that.

I am right with the LAN config tho, with it being tracked to the WAN?

JKnott

@F022Y said in Lit Fibre (UK) IPv6 stopped after powercut:

Looks like my 3 cell connection doesn't support IPv6 so unable to test like that.

????

IPv6 is mandatory for 4G & 5G, though some companies do a poor job with it for tethered devices. What happens if you do that IPv6 test from the phone?

JKnott

@F022Y

That packet capture shows you're pinging a link local address:

Are you pinging the ISPs MAC on the WAN interface? Or something on your local LAN? Link local packets do not pass through a router, so it has to be something directly connected to whichever network you're on.

In that traceroute, I see 4 successful hops, then nothing. This could indicate a routing problem beyond that last one.

F022Y

@JKnott android on 4G and any attempts to ping or routetrace bbc.co.uk it defaults to IPv4.

Address i'm pinging is either bbc or netgate i'll do another now pinging bbc.co.uk...........

Just for giggles i've done 2 for comparison.

Capture the LAN port
packetcapture-igc0-20250318212104.pcap

Capture the WAN port
packetcapture-igc1-20250318211922.pcap