Multiprotocol label switching (MPLS) provides network transport signaling based on MPLS path labels that provide fast routing lookups and high resiliency. The driver for this Extreme Networks MPLS solution is a public safety network deployment with a mission-critical charter distributed across a very large geography. The network handles emergency and public safety traffic across a fiber optic and microwave network. The entire network consists of over 250 non-head-end locations called EnodeB’s which are organized around two head-end locations. In the public safety environment either of the head-end locations are capable of operating the entire network so each EnodeB location maintains both a primary and a secondary MPLS tunnel to each head-end. Service latency and up-time SLA’s exist across the network which is designed with the highest reliability such that each EnodeB maintains an active relationship to all of the head-end devices.
Several technology options were evaluated for use in the network implementation and MPLS was determined to be the best solution able to meet the service objectives. Layer two (L2) ring technologies, while fast and less costly, were determined inadequate to accommodate the active-active path requirements the topology needed. Further, the responsibility for loop prevention in the network needed to be in Layer three (L3) switching elements because of the L3 microwave radio design. Examination of L3 technologies quickly revealed that IP, OSPF, and STP each failed to provide needed failover speed while L3 MPLS met all these requirements.