•Example:Configuring Load Balancing Within Ethernet Ring Protectionfor MX Series
Routerson page 154
EthernetRing Protection Using Ring Instances for Load Balancing
JuniperNetwork MX Series Ethernet Services Routerssupport Ethernet ring protection
(ERP)to help achieve high reliability and networkstability. ERP is used in router or bridge
networksto protectagainst link failure. A single-ring topologyis configured that uses one
specificlink called a ring protection link (RPL) to protectthe whole ring. When all links
areup and running, the RPL blocks traffic and remains idle. However,if a link fails, the
RPLroutes traffic to bypass the failureon the ring.
NOTE: Tolearnhow ERP works in a single-ring topology,see “Ethernet Ring
Protection”on page 145.
MXSeries routersnow support ERP ring instances. Whereas trafficin a single-ring topology
followsthe same path, traffic within ring instancesallows some traffic to pass through
onepath whileother traffic can follow a differentpath. Dividing traffic in this way supports
trafficload balancing in the physical ring.
Ringinstances arelike traffic channels that contain differentsets of virtual LANS (VLANs).
Aring instance is responsiblefor the protection of a subset of VLANs that transporttraffic
overthe physical ring. When ring instances are configuredfor the ring, each ring instance
shouldhave its own RPL owner, an eastand a west interface, and a ring protection link
end.
Eachring instance has a control channel and a specific data channel. A datachannel is
agroup of bridge domain VLAN IDs. All VLAN IDs within the same ring interface share
thesame data-forwardingproperties controlled by the ERP.If no data channel is defined
inthe ring configuration, ERP will only operateon the physical link instead of as a ring
instanceusing logical links.
Whenoperating ERP in a topology with other protocols,the following considerations
shouldbe observed:
•Ifa physical interface is part of an Ethernet ring, it cannot be configuredfor Spanning
TreeProtocol(STP) or Multiple Spanning TreeProtocol (MSTP).
•ERPand Per-VLAN Spanning Tree (PVST)can be configured on the same topology
aslong as PVST doesn'tshare the same VLAN with any Ethernet ring instance
configuredon the physical port.
•IfERP is configured only as a physical ring instance(a ring without a data channel) in
atopology also configured for PVST,ERP checks the PVSTconfiguration on two ring
interfacesand automaticallycreates a data channel excluding VLANs used by PVST.
Related
Documentation
EthernetRing Protection on page 145•
•Example:Configuring Ethernet Ring Protection forMX Series Routers on page 148
147Copyright© 2010, Juniper Networks,Inc.
Chapter13: Ethernet Ring Protection