DHCPv6 PD & Routing Questions

Owen DeLong owen at delong.com
Mon Dec 7 00:05:23 UTC 2015

> On Dec 6, 2015, at 15:03 , Brett Frankenberger <rbf+nanog at panix.com> wrote:
> On Sun, Dec 06, 2015 at 02:20:36PM -0800, Owen DeLong wrote:
>> As an alternative worth considering, it could do this with BGP instead of OSPF.
>> There’s nothing mythical or magical about BGP. A CPE autoconfiguring
>> itself to advertise the prefix(es) it has received from upstream
>> DHCPv6 server(s) to it’s neighbors is not rocket science. In fact,
>> this would mean that the CPE could also accept a default route via
>> the same BGP session and it could even be used to enable automatic
>> failover for mulihomed dynamically addressed sites.
>> Sure, this requires modifying the CPE, but not in a particularly huge
>> way and it provides a much cleaner and more scaleable solution for
>> the ISP side of the equation than OSPF.
>> Most current implementations use RIPv2, but we all know just how icky
>> that is.
> How do you secure that?  Or do you just assume no one will announce
> someone else's prefix?  (I can think of ways to secure it, of course,
> but none of the approaches for having the DHCP server configure some
> sort of prefix access control seem to me to be any better or easier
> than having the DCHP server configure a static route).
> This isn't a problem I face, but if it were, I think I'd solve it by
> having the DHCP server inject the route via BGP with an appropriate
> next-hop.

A perfectly valid alternative… However, lots of people seem determined to use
a routing protocol from the CPE. Given that constraint, I was looking at the options available
and trying to pick the most reasonable among them.

Note: Your concern is equally applicable to RIPv2 and OSPF as it is to BGP.


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