QoS-aware Traffic Protection for Access Rings

In this paper we propose a centralized link layer architecture for providing low latency fault recovery for access rings. This architecture exploits the naturally uneven breakdown of network management responsibilities between the elements of the ring. Administrative operations like ring status checking, fault detection and recovery are aggregated at the HUB. The proposed architecture benefits from a simplified link layer design of the ONU, in addition to lower delays in recovering from faults in the ring. We present an Ethernetbased protocol that realizes our centralized protection model. The design principle of this protocol, responsible for the message passing required to react to topology changes resulting from faults, is to be simple enough to allow quick reaction times. The architecture prioritizes the restoration of network services according to their QoS importance, to ensure that the quality guarantees promised to them are honored at all times. The fault recovery delay of the proposed architecture is evaluated by simulation. In conjunction, the delay and jitter characteristics experienced by different traffic flows during periods of normal operation and faults are measured and compared.