Wednesday, November 17, 2021

L3VPN vs EVPN in service provider

I've always used VPLS and L3VPN (VPNv4) over MPLS and have been happy with the results. Never had much reason to explore EVPN.

I see the benefits of EVPN over VPLS for MAC learning. No arguments about dumping VPLS for EVPN.

But what about replacing L3VPN with EVPN? I can see the push to have the grand unified control plane... Is the experience the same?

-Do you have to mess about with IRBs in a pure L3 scenario? Is that just mixed L2/L3?

-Does an IPv4 EVPN prefix take the same amount of forwarding plane memory as an VPNv4 prefix?

This is controversial, but I've always done Internet in a VRF. Yes, it uses more forwarding pane memory, but it's a beautiful architecture to operate. Total control plane and forwarding plane separation. Full underlay/overlay. Your routing doesn't run in-band anymore. Don't have to do route leaking and rib-groups (on Juniper). It's nice, you should lab it up before you hate on it.

So the next radical step--consider this is service provider--if you're going to run EVPN everywhere, do you dump MPLS for VXLAN? What does that look like slushing around a full set of Internet routes in a VRF over EVPN?

It's all a bit too radical for myself, but VXLAN keeps getting attention. I bet Internet-in-VRF is already too radical for old service provider guys, lol.

Just some hypothetical discussion. I welcome the angry comments :-)



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