[Cerowrt-devel] ipv6 on comcast with 18.06.1

[Anderson, Charles R]

Is udp checksum offload enabled?  If so, tcpdump/wireshark won't see
the actual checksum and assume it is bad.

On Mon, Oct 01, 2018 at 09:12:57AM -0700, Dave Taht wrote:
> hmm... bad udp checksum???
> 
> :/tmp# 09:12:17.404257 IP6 (flowlabel 0xdfff4, hlim 1, next-header UDP
> (17) payload length: 159) fe80::20d:b9ff:fe43:a06c.546 >
> ff02::1:2.547: [bad udp cksum 0x58f4 -> 0xc4a1!]
> On Mon, Oct 1, 2018 at 9:12 AM Dave Taht <dave.taht at gmail.com> wrote:
> >
> > On Mon, Oct 1, 2018 at 8:58 AM Dave Taht <dave.taht at gmail.com> wrote:
> > >
> > > Here you go! Going to go look at the firewall rules in a sec....
> >
> > I changed the rules to allow 547 and 546, no difference. I even
> > flushed the ipv6tables rules entirely,
> > and I'm running without that for a while. I can certainly imagine
> > comcast's dhcpv6 server giving up on me....
> >
> > It's nice to know, btw, someone is still messing with homenet. Having
> > zero funding for
> > too many years burned me out on even trying. But I expected ipv6 to
> > keep working without
> > any more help from me! :(
> >
> > > On Mon, Oct 1, 2018 at 8:45 AM Mikael Abrahamsson <swmike at swm.pp.se> wrote:
> > > >
> > > > On Mon, 1 Oct 2018, Dave Taht wrote:
> > > >
> > > > > Sigh. Once upon a time I used to test this stuff on comcast. So I
> > > > > finally got around to deploying
> > > > > a new 18.06 gateway and ipv6 is busted with comcast.
> > > >
> > > > Can you please email me output from "tcpdump -n -vvv -i <wan> port 546 or
> > > > port 547 or icmp6" as your WAN is trying to get DHCPv6-PD ? Or if you dump
> > > > that to a pcap and email it to me (or make it available somewhere for me
> > > > to download).
> > > >
> > > > I have 18.06.1 working with homenet on WRT1200AC,dual uplinks (two
> > > > different vlans on WAN), getting dual stack from both ISPs, /56 from both,
> > > > and both are announced out on LAN. I even configured bidirectional SQM
> > > > with CAKE on each uplink (250/50 and 250/100 respectively) and it seems to
> > > > do the right thing.