Alcatel-Lucent 6850-48 参照ガイド
OmniSwitch CLI Reference Guide
September 2009
page 16-1
16 Ethernet Ring Protection
Commands
Ethernet Ring Protection (ERP) is a protection switching mechanism for Ethernet ring topologies, such as
multi-ring and ladder networks. This implementation of ERP is based on Recommendation ITU-T G.8032
and uses the ring Automatic Protection Switching (APS) protocol to coordinate the prevention of network
loops within a bridged Ethernet ring.
multi-ring and ladder networks. This implementation of ERP is based on Recommendation ITU-T G.8032
and uses the ring Automatic Protection Switching (APS) protocol to coordinate the prevention of network
loops within a bridged Ethernet ring.
Loop prevention is achieved by allowing the traffic to flow on all but one of the links within the protected
Ethernet ring. This link is blocked and is referred to as the Ring Protection Link (RPL). When a ring fail-
ure condition occurs, the RPL is unblocked to allow the flow of traffic to continue through the ring.
Ethernet ring. This link is blocked and is referred to as the Ring Protection Link (RPL). When a ring fail-
ure condition occurs, the RPL is unblocked to allow the flow of traffic to continue through the ring.
ERP and the Ring Rapid Spanning Tree Protocol (RRSTP) are both used for the prevention of loops in
ring-based topologies but have the following differences in their implementation and functionality:
ring-based topologies but have the following differences in their implementation and functionality:
• RRSTP uses a different destination MAC address for each ring, based on the ring ID. ERP uses the
same destination MAC address for all ERP protocol frames and identifies the ring based on a unique
Service VLAN associated with each ring, which carries the ERP protocol frames.
Service VLAN associated with each ring, which carries the ERP protocol frames.
• When a link failure is detected, RRSTP quickly sets the blocking ports to a forwarding state but relies
on MSTP for actual protocol convergence. ERP does not require any support from MSTP. ERP has an
inherent mechanism to recover from a failed state once the failed link is active again.
inherent mechanism to recover from a failed state once the failed link is active again.
• MSTP determines which ports of a fully active RRSTP ring are blocked. The blocked ports (Ring
Protection Link) for an ERP ring is pre-determined and configured by the user.
• RRSTP requires a ring of contiguous RRSTP nodes. ERP allows non-ERP nodes to participate in the
ring by using the connectivity monitoring capabilities of Ethernet OAM to alert ERP of a link failure
through non-ERP nodes.
through non-ERP nodes.
MIB information for the Ethernet ring protection command is as follows:
Filename:
AlcatelIND1Erp.mib
Module:
ALCATEL-IND1-ERP-MIB