Re: IPv6 routing /48s

From: Christopher Morrow (no email)
Date: Wed Nov 19 2008 - 18:26:15 EST

  • Next message: Jack Bates: "Re: IPv6 routing /48s"

    On Wed, Nov 19, 2008 at 6:03 PM, Jack Bates <> wrote:
    > Christopher Morrow wrote:
    >>
    >> 6to4 v6 addrs are just regular v6 addrs as far as the network is
    >> concerned. if you put a 6to4 addr on your server you are saying that
    >> you don't have native v6 transport to that host(s) and that you are
    >> reachable via the 6to4 tunnel your host presumably has configured.
    >>
    >
    > Sure it's just another address, except the anycast portion of it for dealing
    > with tunnels. It's also usually set to a different label and priority in
    > windows prefix policies (and at least some linux setups). I was referring to
    > the matter of if a windows box will even choose to use 6to4.

    sure... address selection on new connections, standard ipv6 foo for
    end-hosts. routers in the middle don't care, they route to the /16
    route for 2002::/16, or they route to 192.88.99.0/24 ... anycast'd on
    their respective sides of the version#.

    >
    >> 6to4 is just an ip, 128bits long, but an ip... no differentiation is
    >> made in the network for 6to4 vs 'normal v6'... unless someone's
    >> putting up acls, or blackholing 6to4's /16, of course.
    >>
    >
    > Windows and several other end systems use prefix policies to determine if
    > they use IPv6 or IPv4 and even when using IPv6, if they should use the 6to4
    > tunnel or not.
    >

    right, normal address selection rules.

    >> can you explain this a little more? is it possible your v6 packets hit
    >> something like 6pe inside HE and exit to NTT without hitting a
    >>
    >
    > If a router does not a) know how to encapsulate 6to4 and send it over ipv4

    routers in the middle shouldn't/won't do this.. once it's encap'd it
    rides (on v4) to the 192.88.99.1 device that does the 4->6 majics,
    then on to the v6 destination where it rides back to the 'local'
    2002::/16 endpoint where 6->4 encap majics happen then over the v4 to
    you again.

    > to the destination or b) know how to reach a 6to4 anycast address where the
    > packet can be encapsulated into IPv4, the packet is going to get dropped. Of
    > course, you could be right. he.net could be purposefully not sending icmp
    > replies back to 6to4 addresses for other reasons while replying to my
    > non-6to4 addresses. I hesitate to say filter, as it does push the 6to4
    > sourced packets on to other networks.

    hopefully mike's message gets it worked out :)
    -chris


  • Next message: Jack Bates: "Re: IPv6 routing /48s"





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