RE: V4 via V6 and IGP routing protocols

["Pascal Thubert \(pthubert\) via NANOG" <nanog () nanog org>]

Hello Dave:

There's RFC 8950 in the context of BGP. That's a refresher of RFC 5589 which is the one we typically refer to 
internally.

I glanced at homenet too early, and then too late. Too early, it seemed that the protocol would be OSPFv3; no 
discussion. So I left till too late, when the choice was between ISIS and BABEL, and the group would not even consider 
arguments.

RPL seemed to do the trick without the need to define anything new, in my book. It supports multihoming by defining as 
many topologies, no need for source/destination, radios, IoT, mobility, things you'll find at home. But hey, those of 
us who understand RPL were not there at the right time and there we get yet another fragmentation. Not the IETF at its 
best.

Nothing against BABEL, it's neat. Well written specs, much better than we did with RPL. A modernized DV, addressing the 
same space as RIP or EIGRP - though I really like the DUAL piece in EIGRP. More of a core technology than of an 
edge/mobile like RPL, they could be complementary. And then BABEL has a nice dynamic community including openWRT 
developers, that's a huge strength.

Not sure you'll find it in your usual vendor hardware though. 

Keep safe;

Pascal

> -----Original Message-----
> From: NANOG <nanog-bounces+pthubert=cisco.com () nanog org> On Behalf Of Dave
> Taht
> Sent: lundi 4 avril 2022 2:56
> To: Mark Tinka <mark@tinka.africa>
> Cc: NANOG <nanog () nanog org>
> Subject: Re: V4 via V6 and IGP routing protocols
>
> On Sun, Apr 3, 2022 at 12:04 PM Mark Tinka <mark@tinka.africa> wrote:
> > On 4/3/22 13:55, Dave Taht wrote:
> >
> > > Periodically I still do some work on routing protocols. 12? years
> > > ago I had kind of given up on ospf and isis, and picked the babel
> > > protocol as an IGP for meshy networks because I felt link-state had
> > > gone as far as it could and somehow unifying BGP DV with an IGP that
> > > was also DV (distance vector) seemed like a path forward.
> >
> > To scale the IGP, we only carry Loopbacks and interfaces (backbone
> > infrastructure) in the IGP. Many operators have been doing this, for
> > some time now, as a best pratice.
> >
> > Customer routes as well as the DFZ is carried in iBGP.
> >
> > The only issue we have hit with this design is hardware that ships
> > with limited FIB (you're talking 4,000 slots or less). While this can
> > be mitigated with things like 6PE and RFC 3107, there are, now, tons
> > of hardware shipping without this physical restriction. For me, the
> > simpler, the better.
> >
> >
> > > My question for this list is basically, has anyone noticed or
> > > fiddled with babel? It's supported in FRR, bird, and a very small
> > > standalone daemon.
> >
> > Never heard of it as an IGP until now :-).
>
> We'd somewhat foolishly made it a requirement in ietf homenet.
>
> it was how hard adding source specific routing to isis turned out to be
> that turned me.
> At the time I needed simple means to get ipv6 working on multiple consumer
> uplinks.
>
> That later spawned a now mostly dead attempt to unify ipv4 and ipv6
> address distribution called hnet.
>
> I'm fiddling with the new ipv4 over ipv6 stuff now in trying to
> interconnect several ipv4 networks over multiple p2p links.
>
> > Googl'ing:
> >
> >      https://en.wikipedia.org/wiki/Babel_(protocol)
> >
> >
> > > To recap that:
> > >
> > > "V4-via-v6 routing is a routing technique that allows routers with
> > > only IPv6 addresses (including link-locals) to forward IPv4 packets.
> > > It doesn't involve encapsulation (tunnelling), it doesn't involve
> > > translation (NAT), it just works.  For details, please see
> >
> > Since around Junos 9 (2007), OSPFv3 shipped with the ability to carry
> > IPv4 NLRI over an IPv6-only network. We never did implement that, as
> > IS-IS integrated both protocols already. But it's been there for a
> > while for OSPFv3.
> >
> > I don't know when (or if) other vendors implemented the same thing for
> > OSPFv3.
> >
> > That said, nearly any OSPF house I'm aware of still runs both OSPFv2
> > and
> > OSPFv3 side-by-side. I guess folk are probably unprepared to use
> > OSPFv3 for IPv4 NLRI.
>
> I'm sad to hear that those two still have to co-exist. I'd given up on how
> static both routing protocols had become in light of my wireless
> requirements way back then, also memory requirements. Babel had turned out
> to be the only way to get teeny routers to route a few thousand ipv6
> routes as well as ipv4 over wifi mesh networks.
>
> I figured it had made zero penetration outside of that world despite our
> efforts to get it into frr, bird, etc.
>
> > Mark.
>
>
>
> --
> I tried to build a better future, a few times:
> https://wayforward.archive.org/?site=https%3A%2F%2Fwww.icei.org
>
> Dave Täht CEO, TekLibre, LLC