[j-nsp] Interconnecting spines in spine & leaf networks [ was Re: Opinions on fusion provider edge ]

[adamv0025 at netconsultings.com]

> Of Pavel Lunin
> Sent: Friday, November 16, 2018 12:10 AM
> 
> Gert Doering wrote:
> 
> >
> > EVPN is, basically, just putting a proper control-plane on top of MPLS
> > or VXLAN for "L2 routing" - put your MAC addresses into BGP, and it
> > will scale like hell.
> >
> 
> "Like hell" is the right name for it.
> 
> Not that I don't like EVPN but... a) EVPN is not necessarily L2 b)
Ethernet is
> still Ethernet, even over EVPN. In order to announce the MAC over BGP, you
> first need to learn it. With all the consequences and prerequisites.
> And, of course, mapping dynamically leaned stuff to BGP announces comes
> at a cost of making BGP routes as stable as learned MACs.
> 
> Magic doesn't exist.
>
It does and it's called PBB-EVPN
No just kidding :)  

PBB on top of EVPN just brings back the conversational mac learning aspect
of it and solves the scalability issues of pure EVPN (makes BGP independent
of customer mac change rate or mac scale).
But as you rightly pointed out it's still Ethernet with all its problems. 
Though I guess this "simulated" Ethernet is somewhat better than vanilla
Ethernet since you have all these clever features like split horizon groups
designated forwarders, multicast-style distribution of BOM traffic etc...
which depending on who's driving might prevent one from shooting himself in
the foot or provide enough rope to hang with...

adam