In article <[email protected]>, Staffan Thomén <[email protected]> wrote: >Staffan Thomén wrote: >> Greg Troxel wrote: >>> Jeff Rizzo<[email protected]> writes: >>> >>>> I just noticed that a host of mine running as a Xen guest is not >>>> getting (or maybe just sending) ipv6 packets correctly. It's running >>>> pretty much the same as some physical hosts, and the only difference I >>>> can see is the Xen (and vioif) aspect. >>> >>> Are you using a bridge for xvifN.0 on the dom0? >>> >>> Try using ping6 to the link-local (fe80::) addresses. Remember to use >>> %ifname as it appears in ifconfig (other end's address, your ifname). >>> >>> Try running tcpdump in promiscuous mode on both ends. That can hide >>> some mcast programming/filtering bugs to help diagnosis. >>> >>> First, ping the ll address of the xvif from the domU, and vice versa. >>> >> >> The tone I imagined in your email seems to suggest that you know why >> this is happening. >> >> I am seeing this exact problem on my Xen setup, it's a NetBSD 7.1 dom0 >> with 7.1 domU:s using xvif linked to the real wm with a bridge. The >> domUs sometimes become completely unresponsive on ipv6, but then >> recover. ipv4 seems completely unaffected. >> >> Sometimes the dom0 is also unresponsive on v6. >> >> It seems to happen as the domUs are idle, with little to no traffic, >> because one of the VMs host my (v6) irc session and it has stayed up for >> 30+ days. > >Following up on my own mail here, sorry. > >I did some investigation and noticed that listing the entries in NDP on my v6 >gateway showed the nonresponsive (xen domU) hosts as having expired. This >would explain the unresponsiveness. > >Next I dumped the traffic going through the dom0's interface, and saw the >gateway querying ff02::<eui64> of the expired hosts repeatedly but not getting >a reply (this seems like a fallback broadcast). > >So I looked a little closer, and my domU:s were using dhcpcd to handle ipv6, >so I put 'ipv4only' in dhcpcd.conf, set net.inet6.ip6.accept_rtadv to 1 in >sysctl, enabled rtsold and restarted networking. Voila, the problem went away >completely. > >I'm guessing this is a bug in dhcpcd and that it doesn't reply to neighbour >solicitation queries properly when there's a transparent hop like bridge(4) in >the network. The expire times seem to become very short (looks like 60 >seconds) where hosts directly connected get 24 hours. > >Maybe this can help the OP.
I don't know if it is related to the hop, but there was a bug in dhcpcd responding that was fixed... christos
