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Ethernet Ring Protection Switching Overview

Ethernet ring protection switching (ERPS) helps achieve high reliability and network stability. Links in the ring will never form loops that fatally affect the network operation and services availability. The basic idea of an Ethernet ring is to use one specific link to protect the whole ring. This special link is called a ring protection link (RPL). If no failure happens in other links of the ring, the RPL blocks the traffic and is not used. The RPL is controlled by a special node called an RPL owner. There is only one RPL owner in a ring. The RPL owner is responsible for blocking traffic over the RPL. Under ring failure conditions, the RPL owner is responsible for unblocking traffic over the RPL. A ring failure results in protection switching of the RPL traffic. An automatic protection switching (APS) protocol is used to coordinate the protection actions over the ring. Protection switching blocks traffic on the failed link and unblocks the traffic on the RPL. When the failure clears, revertive protection switching blocks traffic over the RPL and unblocks traffic on the link on which the failure is cleared.

The following standards provide detailed information on Ethernet ring protection switching:

  • IEEE 802.1Q - 1998
  • IEEE 802.1D - 2004
  • IEEE 802.1Q - 2003
  • Draft ITU-T Recommendation G.8032/Y.1344, Ethernet Ring protection switching
  • ITU-T Y.1731, OAM functions and mechanisms for Ethernet-based networks

For additional information on configuring Ethernet ring protection switching on EX Series switches, see Example: Configuring Ethernet Ring Protection Switching on EX Series Switches.

For additional information on configuring Ethernet ring protection switching on MX Series routers, see the Layer 2 Configuration Guide for a complete example of Ethernet rings and information about STP loop avoidance and prevention.

Published: 2014-10-13