Ethernet Ring Protection overview

Ethernet Ring Protection (ERP), a nonproprietary protocol described in ITU-T G.8032 (Version 1 and 2), integrates an Automatic Protection Switching (APS) protocol and protection switching mechanisms to provide Layer 2 loop avoidance and fast reconvergence in Layer 2 ring topologies. ERP supports multi-ring and ladder topologies. ERP can also function with IEEE 802.1ag to support link monitoring when non-participating devices exist within the Ethernet ring.

Note

Before configuring ERP, you must configure a VLAN and the ports you require for your deployment.

This chapter describes ERP components, features, and how to configure, and manage ERP.

Configuration Considerations

ERP is supported on the SLX-9540 and the SLX-9640 devices.
You can have a maximum of 255 ERP instances on a device.
Changes to a master VLAN apply to the member VLANs.
If a Topology Group is used, then an ERP instance can be configured only for the Master VLAN.
VLANs used for ERP must be pre-configured on the device along with interfaces in L2 mode.
ERP cannot be configured if STP/RSTP/MSTP/PVST is running, and STP/RSTP/MSTP/PVST cannot be configured if ERP is running.
Sub-50 msec convergence is achieved with a 4-device Ring topology on 1-RU devices. If the number of nodes in the topology increases beyond this, there will be a small linear increase in convergence time.
Maintenance Domain (MD), Maintenance Association (MA), and Maintenance End Points (MEPs) need to be configured before using dot1ag compliance for a specific ERP instance.