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So this is the fourth blog on EVPN, the previous blogs covered the following topics:
- EVPN basics, route-types and basic L2 forwarding
- EVPN IRB and Inter-VLAN routing
- EVPN single-active multi-homing
This post will cover the ability of EVPN to provide all-active multi-homing for layer-2 traffic, where the topology contains two different active PE routers, connecting to a switch via a LAG, the setup is similar to the previous labs. Due to some restrictions and in the interests of simplicity, this lab will cover all-active multi-homing for a single VLAN only, (VLAN 100 in this case) consider the network topology:

The topology and general connectivity is the same as the other previous examples, the two big differences are that only VLAN 100 is present here and the connectivity between MX-1 and MX-2 is now using MC-LAG.
The first consideration that needs to be made when running EVPN in all-active mode, is that it must connect to the upstream devices using some sort of LAG, or MC-LAG – consider the wording from the RFC 7432:
https://tools.ietf.org/html/rfc7432#section-14.1.2
“If a bridged network is multihomed to more than one PE in an EVPN network via switches, then the support of All-Active Continue reading