Hi, Yesterday, I noticed that one of my platforms had become unreachable over IPv6. This platform is connected to a Clearfog, which uses the Marvell 88e6176 switch.
The setup is: (rest of network) | | | | | | | Source ---- Netgear switch ---- Clearfog switch ---- Target ^ ^ ^ lan1 lan5 eth2 port 4 port 0 Both the source and target could ping the IPv6 link-local address on the clearfog, and IPv4 traffic was fine. The source was attempting to ping the target, and the target had been attempting to mount a NFS share over IPv6 (and failing.) Statistics from the Clearfog switch - port 0 is the target, port 4 is the netgear switch, port 5 is the CPU port: Statistic Port 0 Port 1 Port 2 Port 3 Port 4 Port 5 Port 6 in_multicasts: 27670 0 0 14552 78196 1674 0 out_multicasts: 439 0 331 332 331 114860 334 As you can see, very few multicast packets have been sent out any of the ports. Running tcpdump on the source machine: 21:31:48.805654 xx:xx:xx:15:37:dd > 33:33:ff:00:00:05, ethertype IPv6 (0x86dd), length 86: fd8f:xxxx:xxxx:xxxx:222:68ff:fe15:37dd > ff02::1:ff00:5: ICMP6, neighbor solicitation, who has fd8f:xxxx:xxxx:xxxx:200:ff:fe00:5, length 32 tcpdump on the clearfog for port 4: 21:31:48.807640 xx:xx:xx:15:37:dd > 33:33:ff:00:00:05, ethertype IPv6 (0x86dd), length 86: fd8f:xxxx:xxxx:xxxx:222:68ff:fe15:37dd > ff02::1:ff00:5: ICMP6, neighbor solicitation, who has fd8f:xxxx:xxxx:xxxx:200:ff:fe00:5, length 32 The port connected to the target doesn't see these multicast messages which are intended for it. However, I am able to see messages multicasted from the target, which is trying to solicit a different machine on my network: 21:33:22.394653 00:00:00:00:00:05 > 33:33:ff:10:1b:e6, ethertype IPv6 (0x86dd), length 86: fd8f:xxxx:xxxx:xxxx:200:ff:fe00:5 > ff02::1:ff10:1be6: ICMP6, neighbor solicitation, who has fd8f:xxxx:xxxx:xxxx:214:fdff:fe10:1be6, length 32 but these neighbour solicitations are also not forwarded to through the switch to the rest of the network. Tweaking the DSA switch port register 4 (which had a value of 0x0433) to 0x043b resolved the issue - multicast traffic started to egress these ports, and the neighbour solicitations then worked. I thought maybe this was a 4.16 regression, but it seems my other clearfog has a similar register setup, so I'm not sure. I'm pretty sure that it used to work at some point, as I'm a heavy user of IPv6 internally, and I'm quite certain that I would have noticed a failure such as this. The setup on the target is eth2 is part of a Linux bridge device. -- RMK's Patch system: http://www.armlinux.org.uk/developer/patches/ FTTC broadband for 0.8mile line in suburbia: sync at 8.8Mbps down 630kbps up According to speedtest.net: 8.21Mbps down 510kbps up