The use of MPLS tunnels provides a way to scale the core while offering fast failover times using MPLS FRR. In environments where Ethernet services are deployed using native Ethernet backbones, Ethernet tunnels are provided to achieve the same fast failover times as in the MPLS FRR case. There are still service provider environments where Ethernet services are deployed using native Ethernet backbones.
The Nokia VPLS implementation offers the capability to use core Ethernet tunnels compliant with ITU-T G.8031 specification to achieve 50 ms resiliency for backbone failures. This is required to comply with the stringent SLAs provided by service providers in the current competitive environment. The implementation also allows a LAG-emulating Ethernet tunnel providing a complimentary native Ethernet E-LAN capability. The LAG-emulating Ethernet tunnels and G.8031 protected Ethernet tunnels operate independently. For more information, see the 7450 ESS, 7750 SR, 7950 XRS, and VSR Services Overview Guide, "LAG Emulation using Ethernet Tunnels".
When using Ethernet tunnels, the Ethernet tunnel logical interface is created first. The Ethernet tunnel has member ports that are the physical ports supporting the links. The Ethernet tunnel controls SAPs that carry G.8031 and 802.1ag control traffic and user data traffic. Ethernet Service SAPs are configured on the Ethernet tunnel. Optionally, when tunnels follow the same paths, end-to-end services are configured with same-fate Ethernet tunnel SAPs, which carry only user data traffic, and share the fate of the Ethernet tunnel port (if properly configured).
When configuring VPLS and B-VPLS using Ethernet tunnels, the services are very similar.
For examples, see the IEEE 802.1ah PBB Guide.