Juniper Networks 10.4

Everynode on the ring is one of two types:

•RPLowner node—Thisnode owns the RPL and blocks or unblocksthe RPL as conditions

require.This node initiates the R-APS message.

•Normalnode—All other nodes on the ring (that is, those that are not the RPL owner

node)operate as normal nodes and have no special roleon the ring.

Inaddition to roles, each node on the Ethernet ring can be in one of severalstates:

•Init—Thenode is not yet participating in the ring.

•Idle—Thenode is performingnormally (there is no link failure on the ring). In this state,

trafficis unblocked on both ring ports, exceptfor the RPL owner node, which blocks

theRPL port (the other RPL owner port is unblocked).

•Protection—Whena failureoccurs on the ring, a normal node will have traffic blocked

onthe ring port that connects to the failed link. The RPL owner,if it is not at one end

ofthe failed link, will then unblock the RPL port so both ports are active.

NOTE: TheR-APS protocoldoes not detect the number of RPL owner nodes

configuredon the ring. You must configureonly one RPL and RPL owner per

ringor protection switching will not work properly.

Ethernetring protection only works when one link on the ring fails.Multiple link failures

willbreak the ring and cause protection switching to fail.

Severalrestrictions apply to Ethernet ring protection:

•TheEthernet ring protection configured asa single instance only works at the physical

level(adjacent nodes must be directly connected).The ring protection operates at

theinterface (port) level and not at the VLAN level.

•Manual(command-based) switching to protectionmode is not supported.

•Nonrevertiveswitching is not supported.When the link failure is cleared, traffic always

returnsto normal operation.

•Theinterconnection of multiple rings forprotection purposes is not supported.

Youcan configure Ethernetring protection to optomize traffic load-balancing byusing

multipleringinstances. For more information about multiplering instances, see “Ethernet

RingProtection Using Ring Instances for LoadBalancing” on page 147

Documentation

MXSeries Ethernet Services Routers SolutionsPage•

•Example:Configuring Ethernet Ring Protection forMX Series Routers on page 148

•Example:ViewingEthernet Ring Protection Status—NormalRing Operation on page 171

•Example:Viewing Ethernet Ring ProtectionStatus—Ring Failure Conditionon page 172

•EthernetRing Protection Using Ring Instances for LoadBalancing on page 147

Junos10.4 MX Series Ethernet ServicesRouters Solutions Guide