D-Link DGS-6600-48TS Configuration Guide - Page 184

Volume 3 - Layer 2 Configurations Chapter Overview R-APS (NR, RB) messages, RPL neighbor blocks RPL and others unblock blocked ports, and ERP instance returns to "Idle" state. Multiple Ethernet Ring Topology When the ring nodes grow gradually in single Ethernet ring, this large ring may be broken and causes traffic segmentation. For the single ring topology which is depicted in the diagrams below, if there are two or more links between ring nodes have occurred link failure, the single ring will not keep connectivity between all ring nodes. In order to provide scalability and reliability, large single ring will be divided to multiple rings which are interconnected. For the multiple rings topology which is depicted below, even if two links have occurred link failure, all ring nodes will still keep connectivity by using common link. The multiple rings topology with ERPS can be classified two types, "Multiple ERP Instances" and "Multi-Ring/ladder network". These two types are described on next two sections. The maximum created ERP instances on the device should depend on project definition. RPL RPL RPL1 Sub-Ring Major-Ring RPL2 Multiple ERP instances An Ethernet ring topology may have multiple traffic channels which are grouped into different sets of VLANs. In order to protect these traffic channels, multiple ERP instances are defined and each ERP instance is responsible with one service protected channel and has its own following features. Instance-ID (Ring-ID) RPL Owner/Neighbour Node and RPL R-APS controlled channel and service protected channel ERP Control Process And, the link failure and recovery events for each ERP instance are independent. Topology of multiple ERP instances is depicted below. There are two ERP instances that have its own RPL (RPL1 and RPL2) and are used to avoid loop of its own service protected channels (blue and red channels). For the interconnection nodes, it shall create two ERP instances. Interconnection Nodes RPL2 RPL1 For the following diagrams, two or more ERP instances have the same service protected channel (blue channel). It may cause a super loop when the shared link failure and two EPR instances block this link and unblock RPL simultaneously. DGS-6600 Configuration Guide 184