Carrier Ethernet ”label” scalability

Ethernet is becoming one of the dominant aggregation technologies for carrier transport networks. Because it is a LAN technology, native bridged Ethernet does not fulfil all carrier requirements. Several schemes have been proposed to allow Ethernet to fulfil such requirements. Carrier Ethernet technologies rely on domain-wide or local label-based forwarding, although some of them use a smaller label size and different scope than existing label switching technologies (like Multi-Protocol Label Switching). Therefore, they can present label scalability issues, in the sense that a connection request can be blocked due to label unavailability. This article studies label scalability limitations of two of the existing carrier Ethernet solutions, Provider backbone bridges Traffic Engineering (PBB-TE) and Ethernet VLANLabel Switching (ELS). The applicability of existing techniques (like aggregation and label merging) that can overcome or reduce these limitations is evaluated. Additionally for PBB-TE a specific technique called VLAN-reutilization is formalized and the complexity of optimally applying it, is studied. The techniques are evaluated over an online routing scenario, results show that both solutions can present label scalability limitations when used without the studied techniques. These limitations can be greatly overcome by implementing the techniques.