[186244] in North American Network Operators' Group
Re: DHCPv6 PD & Routing Questions
daemon@ATHENA.MIT.EDU (Owen DeLong)
Sun Dec 6 17:24:47 2015
X-Original-To: nanog@nanog.org
From: Owen DeLong <owen@delong.com>
In-Reply-To: <CAPkb-7D51zcgzN3SHFY7o-d2cWo+FNMQy7go3HsSyY_+6G8Xuw@mail.gmail.com>
Date: Sun, 6 Dec 2015 14:20:36 -0800
To: Baldur Norddahl <baldur.norddahl@gmail.com>
Cc: "nanog@nanog.org" <nanog@nanog.org>
Errors-To: nanog-bounces+nanog.discuss=bloom-picayune.mit.edu@nanog.org
> On Dec 6, 2015, at 08:45 , Baldur Norddahl <baldur.norddahl@gmail.com> =
wrote:
>=20
> On 6 December 2015 at 06:18, Mark Andrews <marka@isc.org> wrote:
>=20
>>> Are you really suggesting that a residential ISP accept routes =
advertised
>>> from their customer=E2=80=99s CPE? Really?
>>=20
>> PD is used internally as well as externally, and with a little bit
>> of crypto to prove the assigned address belongs to them there really
>> isn't a reason a CPE device couldn't announce a address to a ISP.
>> It would also allow BCP38 filters to be built rather than using RFP
>> which is only a approximate solution.
>>=20
>=20
> Do you envision that the CPE runs OSPFv3 or something else? Would that
> scale? I am not an OSPF expert, but thousands of CPEs in an OSPF =
domain
> does not sound like a sane thing.
As an alternative worth considering, it could do this with BGP instead =
of OSPF.
There=E2=80=99s 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=E2=80=99s 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.
> What is the advantage? The prefix has been assigned to the CPE. If the =
CPE
> does not advertise the prefix it just goes to the null route. What is =
the
> use case where you want a prefix assigned to a CPE but _not_ routed to =
the
> same CPE?
_not_ routed is not the only consideration here.
routed via alternative paths may be worthy of consideration.
Owen
