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

[Krzysztof Szarkowicz]

Hi Rob,

Indeed, for single-active, no LAG is needed, as only DF PE will allow traffic, and other PEs (nDF) will block all the traffic for given VLAN. So, you can deploy single-active. It is supported on MX (incluidng service carving for VLAN-aware bundle).

Thanks,
Krzysztof

> On 2019-Apr-18, at 09:33, Rob Foehl <rwf at loonybin.net> wrote:
> 
> 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