[arin-ppml] v6 AFI over v4 BGP (was Preemptive IPv6 assignment)

Michael Richardson mcr at sandelman.ca
Tue Oct 12 20:55:00 EDT 2010

>>>>> "Wes" == Wes E IV George <George> writes:
    Wes> [WES] Change of subject line to reflect new topic.  This does
    Wes> work. It just doesn't work particularly *well* because a number
    Wes> of router vendors have implemented next-hop handling strangely,
    Wes> where the route announcement gets dropped by the neighboring
    Wes> router because it's announced with a v4-mapped v6 next-hop or a
    Wes> link-local next-hop, both seen as invalid by the upstream
    Wes> router due to no route to next-hop. We're using a single IPv4
    Wes> BGP session for both IPv4 and IPv6 unicast AFs for our iBGP
    Wes> sessions, but as it was we had to add route-policies to force
    Wes> the correct next-hop to be set (pending resolution of a couple
    Wes> of bugs), and configuring next-hop-self doesn't always
    Wes> fix. Because we have no way of knowing whether $CPE_vendor
    Wes> supports it correctly in the combination of software and
    Wes> hardware that our customers are running, we default to separate
    Wes> BGP sessions per AF for eBGP.

    Wes> That said, I don't think it would be as simple as you paint it,
    Wes> because even if you assume that the PTP link addresses sort
    Wes> themselves out automagically, if you're doing BGP, how do you

Well, really I would be very worried if it was as simple as I'd
suggested :-)

The ideal situation is really that I'd want people to say, "hey, what
are these complaints in my logs about invalid IPv6 nexthops from
provider FOO? "

    Wes> I'm not convinced that this would fundamentally change the
    Wes> speed of deployment anyway. Setting up BGP with your upstream
    Wes> to support IPv6 is easy in comparison to actually having an
    Wes> upstream that supports it and getting all of the devices in
    Wes> your enterprise to be able to do something with that prefix you
    Wes> got.

Again, a provider with errors in their logs because their customers are
ahead of them is a good thing.

]       He who is tired of Weird Al is tired of life!           |  firewalls  [
]   Michael Richardson, Sandelman Software Works, Ottawa, ON    |net architect[
] mcr at sandelman.ottawa.on.ca http://www.sandelman.ottawa.on.ca/ |device driver[
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