Re: Couple of IPv6 Questions.

From: Brian Haley (Brian.Haley_at_nospam_hp.com)
Date: 05/27/03

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    Date: Tue, 27 May 2003 20:57:03 GMT

    David Malone wrote:
    > I've been fiddling around with IPv6 on Tru64 and there's a couple
    > of things I haven't been able to figure out. First, I haven't been
    > able to find a command that displays the neighbour cache - something
    > like ndp on KAME stacks.

    # netstat -N

    I'll add that to my list of documentation that needs updating.

    > Second, I've been trying to set up a configured tunnel to a FreeBSD
    > host. I've tried both manually and with ip6_setup, the manual config
    > goes like this:
    >
    > iptunnel create -I ipt0 _v4_dest_addr_ _v4_source_addr_
    > ifconfig ipt0 ipv6
    > ifconfig ipt0 inet6 _v6_source_addr_
    > ifconfig ipt0 up
    >
    > I find that if I ping the all-nodes multicast address from the
    > FreeBSD host, then I get a reply from the Tru64 machine. If I try
    > pinging the _v6_source_addr_ I don't get a reply at all (I can see
    > the incomming packet count going up in netstat -in, but the box
    > doesn't seem to generate any replies, or if it does they don't make
    > it on to the wire).

    The problem is that neither machine has a route to the v6 "network"
    associated with the addresses you added (check netstat -rnf inet6).
    The IPv6 output errors are probably going up on each system:

    # netstat -p ipv6
    ...
            21 packets not transmitted due to error
    ...

    Here's an example that will work:

    Host 1:

    # iptunnel create -I ipt0 host2 host1
    # ifconfig ipt0 ipv6 up
    # ifconfig ipt0 inet6 2000:7::1
    # route add -net -inet6 2000:7::/64 2000:7::1 -interface -dev ipt0

    Host 2:

    # iptunnel create -I ipt0 host1 host2
    # ifconfig ipt0 ipv6 up
    # ifconfig ipt0 inet6 2000:7::2
    # route add -net -inet6 2000:7::/64 2000:7::2 -interface -dev ipt0

    Netstat -rnf inet6 will have a route to the 2000:7::/64 network through
    the ipt0 interface now:

    2000:7::/64 2000:7::1 US 0 7 ipt0
    2000:7::1 2000:7::1 UHL 1 4 ipt0

    And you won't have to use "-I ipt0" with ping or traceroute.

    We assumed that most users will configure tunnels on routers, which
    will automatically configure all of this for you, as well as advertise
    and receive routing updates through the tunnel.

    -Brian Haley, Tru64 Unix Networking

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