L3VPN services are widely deployed in service provider networks, and their reliable operation over SR-MPLS is a requirement. We verified that the multi-vendor SR-MPLS underlays with different IGP control planes are able to successfully support L3VPN services without facing issues with forwarding behavior. Using the topologies below, we verified that L3VPN services can be established over an SR-MPLS network with different IGP control planes. We executed the test in two single-domain variants. In the IS-IS case, we built an SR-MPLS domain with three spine nodes and established MP-BGP between all Provider Edge (PE) devices to exchange VPN routes. In the OSPF case, we repeated the same procedure using a single spine node while keeping the PE-side service configuration unchanged. For the two scenarios, we verified the underlay control plane by ensuring that segment routing information is advertised correctly and that MPLS label installation and forwarding entries are as expected. We then enabled the L3VPN service and generated traffic for IPv4 L3VPN traffic between PE devices. The traffic was forwarded from PE to PE without loss. This confirmed that VPN route exchange and SR-MPLS label forwarding across a multi-vendor setup worked correctly.
Note: The traffic generator was connected to a switch that was linked to all PE devices, enabling simultaneous communication with all PEs.