[c-nsp] Multihomed OTV on CSR Lab - Mac Address Issue

[James Bensley]

On 30 January 2018 at 18:29, Aaron Gould <aaron1 at gvtc.com> wrote:
> Thanks....
>
> "With regards to the load-sharing in L2
>  -problem is you'll never get IP like load-sharing in L2 since Ethernet is
> fundamentally flawed in this regard as it just can't associate same mac
> address with two ports."
>
> I thought with bgp-mac-routes in evpn, you could engineer traffic with same
> knobs used in bgp-ip-routes. ?
>
> I thought with evpn, you could have active-active multi-homed forwarding
> across 2 ports, 2 CE's. ?
>
> -Aaron

Hi Aaron,

That is correct. EVPN does support multi-active forwarding with a
single designated forwarding PE for BUM traffic. It's "closer" to a
typical L3 VPN in that the customer MAC addresses (instead of IP
prefixes) are learnt in the control-plane. If using BGP for example as
your control-plane, ECMP now becomes an option because you have
multiple MAC routes in BGP, each with a different next-hop and label
(if using MPLS based EVPN). This is the same as a dual-homed CPE in a
L3 VPN. MACs are stored in a MAC-VRF like an IP VRF and each MAC-VRF
has a unique route distinguisher, also like an IP VRF.

It's easy to get caught up in new jazzy technologies but I do really
like EVPN [1] because L2 VPNs and L3 VPNs start to operate with more
similar properties.

Cheers,
James.


[1] We don't have any live EVPN yet, I'm just lab testing it at
present to better understand it.