No, no solution so far except drastic ones that I have employed which highly likely will not apply to you.

Works just fine here. Facebook still will not open.

Not sure what's exactly happened at TM side.

Currently, i'm using Hurricane Electric IPv6 tunnel for my IPv6 connection.

Maybe reading this YouTube video buffering issue on IPv6 enabled networks blogspot entry can give you hint on how to fix the problem.

Noted anything else?

That's all from me. Thanks for your willingness to tell TM about this matter.

OMG, MSS clamping to 1392 DOES THE TRICK!



I've tried MSS clamping before, but not at 1392, therefore I assume MSS clamping will not solve the problem.
wKkaY should add this to the front page - no need for people to have problems like this.

Typically one would clamp it to PMTU and let the kernel do the math. Do you have the option for that?

Mikrotik can do that, but only for IPv4 traffic. For IPv6, MSS clamping has to be done manually.

Mine seems to have it. I can add the mangle rule, although I can't confirm whether it actually works. Version 6.4 FWIW.

Having said that, technically it's not pure in the sense that there's something in the middle meddling with the IP payload. Lemme see whether there's any IPv6 spec that addresses the PMTU problem.

If I set up the PPP profile to change the MSS, Mikrotik will only add two rules in "/ip firewall mangle" section. The "/ipv6 firewall mangle" section will still be empty. This is a known issue with routerOS as shown at http://forum.mikrotik.com/viewtopic.php?f=2&t=51117 amongst other places.

Do you know how to tell routerOS to add the appropriate rules to "/ipv6 firewall mangle" when change MSS is enabled in the PPP profile?

@asellus Are you using Streamyx 2Mbps? Just want to know.

Oh I didn't know they would add those rules automatically. Mine doesn't add them for IPv4. In Linux, the MTU mangling is normally done in rp-pppoe userspace client, so it isn't necessary to create iptables rules. I don't know if Mikrotik uses the same pppoe client implementation.

So now I understand what you mean by "manually". What I meant wasn't automatic as in remove the need to manually add clamping rules. Just to remove the manual MSS calculation, by using a rule like:

Hehehe nice one bro :-) dunno got another admin playing with mikrotik also

In routerOS, to do MSS clamping, you have to use iptables and/or ip6tables. The PPPoE dialer of routerOS lacks many features that even D-Link DIR-615 dialer has.

Your rule seems to works though. Although I wonder why MSS clamping to 1432 that I done earlier doesn't work, while it works with 1392.

I have Streamyx BB 4MB and BB 1MB. Both works well with IPv6.

When I'm free (after I catch up to all the work I missed from being sick) I'll set up an experiment to figure out this MTU problem. In theory... PMTU discovery should address this. But why isn't it?

Thanks for sharing. Was wondering all the while was is going on. Didn't expect the implementation of IPV6 bringing this kind of impact.

Hi MX510. May i know what is the TM answer for my question?

Thank you.

Actually, clamping the MSS to 1392 seems to work. What router did you use?

Ooo, ok. I wish i can upgrade my line to Streamyx 4 Mbps soon.