[j-nsp] EVPN all-active toward large layer 2?

[Rob Foehl]

On Thu, 18 Apr 2019, Wojciech Janiszewski wrote:

> You have effectively created L2 loop over EVPN, so to cut it you need a
> link between bridged network and EVPN to be a single link. There is no STP
> in EVPN.
> If you need two physical connections to between those networks, then LAG is
> a way to go. MC-LAG or virtual chassis can be configured on legacy switches
> to maintain that connection. ESI will handle that on EVPN side.

On Thu, 18 Apr 2019, Krzysztof Szarkowicz wrote:

> As per RFC, bridges must appear to EVPN PEs as a LAG. In essence, you need to configure MC-LAG (facing EVPN PEs) on the switches facing EVPN PEs, if you have multiple switches facing EVPN-PEs. Switches doesn’t need to be from Juniper, so MC-LAG on the switches doesn’t need to be Juniper-flavored. If you have single switch facing EVPN PEs -> simple LAG (with members towards different EVPN PEs) on that single switch is OK.

Got it.  Insufficiently careful reading of the RFC vs. Juniper example 
documentation.  I really ought to know better by now...

Unfortunately, doing MC-LAG of any flavor toward the PEs from some of 
these switches is easier said than done.  Assuming incredibly dumb layer 2 
only, and re-reading RFC 7432 8.5 more carefully this time...  Is 
single-active a viable option here?  If so, is there any support on the MX 
for what the RFC is calling service carving for VLAN-aware bundles for 
basic load balancing between the PEs?

Thanks for setting me straight!

-Rob