Erp And Rrstp Differences - Alcatel-Lucent OmniSwitch 6850-48 Network Configuration Manual

Configuring ERP

ERP and RRSTP Differences

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:
•
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.
•
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.
•
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.
OmniSwitch AOS Release 6 Network Configuration Guide September 2009
ERP Overview
page 14-7