... And while on the subject of scaling, please keep in mind that BGP
only stores L1VPN routes on PEs that have sites of that VPN connected
to them, and on an RR if used, but *not* on any of the P routers. In
contrast, rfc5252 (OSPF for L1VPN autodiscovery) results in storing
*all VPN TE information for all the VPNs* on *all* the IGP nodes, both P
and PE. So, clearly BGP-based approach scales better than OSPF-based
This is not true in case of multi-instance OSPF: one can build an overlay interconnecting PEs via one or small number of Ps using IPinIP tunnels
and run in this overlay an instance of OSPF specifically designated for distribution of L1VPN information. In this case the OSPF solution won't scale any worse than the BGP approach. Note. that rfc252 never said that the instance of OSPF used for flooding of the L1VPN information must be the same instance that is used for the distribution of IP-related LSAs.