[c-nsp] VxLAN EVPN decision

[adamv0025 at netconsultings.com]

> Satish Patel
> Sent: Wednesday, April 29, 2020 8:10 PM
> To: Cisco Network Service Providers <cisco-nsp at puck.nether.net>
> Subject: [c-nsp] VxLAN EVPN decision
> 
> Folks,
> 
> when someone should decide to go with VxLAN EVPN base clos design or
> Tier 3 (core/dist/access) design? what criteria decide which design would
be
> best fix?
> 
> Following criteria in my mind.
> 1. North/South  Vs east-west traffic
> 2. BUM suppression ( Classic design doesn't help here) 3. If you hate STP
(but
> vPC is exception) 4. scale (STP has limitation because of large L2) 5.
> complexity (Classic Tier 3 is easy to configure and manage)
> 
> what other things people keep in mind to decide go with Tier 3 vs Clos
> (VxLAN+EVPN)
>
I'd go with MPLS+EVPN -nowadays all data-centre gear supports MPLS in
addition to IP. 
With regards to the 3-tier vs folded clos model (vs benes model) I guess one
could evaluate them from the modularity viewpoint for example -more
precisely how many classes of nodes you want to maintain, 
3-tier =  3 types, 
Clos = 2 types, 
Benes =  1 type, 
 - and how this affects your scaling. 
 
adam