Possible Routing Problem in HE Network

[DJX]

Does this link work for you?
http://[2620:106:e001:f00f::34]/images/public/amz/5/2/1/0/4003091900125_500W_500H.jpg

Unfortunately, I'm not familiar with SonicWall, so I don't know how to set MTU/MSS. Maybe someone else can chime in?

Negative, that link does not work.
AFAIK, SonicWALL only allows you to change the Link MTU advertised for physical interfaces.

Did Pandora say they were going to continue to work on this issue?

[steve1515]

You could try and lower the MTU on your WAN interface to see if that forces the packets going thought the tunnel to be lowered as well. I'm interested to see if this would work for you.

I told Pandora everything works with the MSS change, but haven't heard back if they are still looking at anything. I think they are declaring it fixed though.

--Steve

[DJX]

You could try and lower the MTU on your WAN interface to see if that forces the packets going thought the tunnel to be lowered as well. I'm interested to see if this would work for you.

I told Pandora everything works with the MSS change, but haven't heard back if they are still looking at anything. I think they are declaring it fixed though.

--Steve

Yeah that doesn't do anything.
If you've ever seen the configuration pages of SonicWALLs, you'd know how frustrating it is how they only let you configure certain aspects.
In the interfaces page alone, you have to select a radio button for managing either IPv4 or IPv6 side of the interfaces.
The IPv6 side WAN interface isn't doing anything so changing the MTU there is useless.
The IPv4 side WAN interface needs to be at 1500 because that's what my ISP gives me.

The IPv6 tunnel interface just has a few boxes for the address objects and that's about it.

For the IPv6 LAN interface, the only MTU you can configure is the Link MTU advertised in the RA, so that's useless.

How did you get to talk to Pandora anyway?
I tried their contact page and I'm getting nothing, no response.

[steve1515]

You should be able to use a smaller MTU than 1500 on your IPv4 WAN interface. Try something like 1280 to test it out. Because the tunnel is over IPv4, it should force your packets to be smaller for both IPv4 and IPv6. If that works, you can then start increasing it until it breaks again.

I used the contact page. It was a web form to start and then they contacted me via email. It took a couple of days for them to get back to me. How many days have you waited? Maybe you could try again. Also check your spam folder, I had one support email end up in there. I almost missed it.

--Steve

[DJX]

You should be able to use a smaller MTU than 1500 on your IPv4 WAN interface. Try something like 1280 to test it out. Because the tunnel is over IPv4, it should force your packets to be smaller for both IPv4 and IPv6. If that works, you can then start increasing it until it breaks again.

I used the contact page. It was a web form to start and then they contacted me via email. It took a couple of days for them to get back to me. How many days have you waited? Maybe you could try again. Also check your spam folder, I had one support email end up in there. I almost missed it.

--Steve

It's been two days since I submitted the form on their website.
I tried to lower the MTU on the IPv4 WAN interface to 1280 and it didn't help with the test URL:
http://[2620:106:e001:f00f::34]/images/public/amz/5/2/1/0/4003091900125_500W_500H.jpg
Still doesn't load.
:-(

[nfawcett]

I can confirm the same behavior that steve1515 reported in my own home network using a HE IPv6 tunnel.  It's interesting that the MSS/MTU adjustment got it working, but what this really tells me is that PMTU discovery is not functional somewhere along this path.  End users should not have to play games with MSS/MTU.

[steve1515]

Do you know if there's a way to determine where PMTUD breaks?

[DJX]

Thanks for writing in. Our Network Operations team is aware of the issue with IPv6.

It looks like you might also be aware of the MSS settings. Most of our listeners have had luck with MSS set to 1440 or 1420, which has been recommended by our Network team.

I'm afraid other than this setting, our Network team does not have another fix at the moment. They are currently investigating a longer term solution.

Sorry for any inconvenience. Please let me know if I can help with anything else.

Thanks so much for listening!

Looks like there is nothing I can do since I can't adjust my MSS or MTU for tunnel interfaces on a SonicWALL.

[DJX]

I asked about an ETA...

I'm afraid we don't have an ETA as of now, but I can assure you our Network team is currently looking into this issue. They hope to have a solution, or at least more troubleshooting to offer, soon.

Sorry again for any trouble. Feel free to drop us another line in if you have questions in the future.