Ethernet Ring Protection Switching (ERPS) is a protocol defined by the International Telecommunication Union - Telecommunication Standardization Sector (ITU-T) to eliminate loops at Layer 2. Because the standard number is ITU-T G.8032/Y1344, ERPS is also called G.8032. ERPS defines Ring Auto Protection Switching (RAPS) Protocol Data Units (PDUs) and protection switching mechanisms.

ERPS has two versions:
  • ERPSv1 released by ITU-T in June 2008, and

  • ERPSv2 released in August 2010.

EPRSv2, fully compatible with ERPSv1, provides the following enhanced functions:
  • Multi-ring topologies, such as intersecting rings

  • RAPS PDU transmission on non-virtual-channels (NVCs) in sub-rings

  • Forced Switch (FS) and Manual Switch (MS)

  • Revertive and non-revertive switching

Generally, redundant links are used on an Ethernet switching network such as a ring network to provide link backup and enhance network reliability. The use of redundant links, however, may result in creating network loops, causing broadcast storms and rendering the MAC address table unstable. As a result, communication quality deteriorates, and communication services may even be interrupted.

Ethernet networks demand faster protection switching. STP does not meet the requirement for fast convergence.

ERPS, a standard ITU-T protocol, prevent loops on ring networks. It optimizes detection and performs fast convergence. ERPS allows all ERPS-capable devices on a ring network to communicate.

Benefits of ERPS include:
  • Prevents broadcast storms and implements fast traffic switchover on a network where there are loops.

  • Provides fast convergence and carrier-class reliability.

  • Allows all ERPS-capable devices on a ring network to communicate.