Erps - WAGO 852-1305 Manual

WAGO-ETHERNET-Zubehör 852
852-1305 8/4-Port 100BASE-T/1000BASE-SX/LX
7.2.7

ERPS

The ERPS ("ETHERNET Ring Protection Switching") function implements a
protection switching mechanism for ETHERNET layer ring topologies according
to ITU-T standard G.8032. The ERP ("ETHERNET Ring Protection") protects
ETHERNET traffic in a ring topology and ensures that no loops are within the
ring in the ETHERNET later. Looping is prevented by blocking traffic on either a
predetermined link or a failed link.
The ETHERNET ring protection functionality includes the following:
• Loop avoidance
• Use of learning, forwarding and filter database (FDB) mechanisms
Loop avoidance in an ETHERNET ring is achieved by guaranteeing that, at any
time, traffic may flow on all but one of the ring links. This particular ring link
serves as a reserve connection and is called an RPL ("Ring Protection Link"). In
normal operation, it is blocked and not used for service traffic. A specific
ETHERNET ring node, the "RPL Owner" node, is responsible for blocking traffic
at one end of the RPL. Under an ETHERNET ring failure condition, the "RPL
Owner" node is responsible for unblocking its end of the RPL, unless the RPL has
failed, allowing the RPL to be used for traffic. The ETHERNET ring node
adjacent to the RPL, the "RPL Neighbor" node, may also participate in blocking
or unblocking its end of the RPL.
The ETHERNET rings can support a multi-ring/ladder network that consists of
conjoined ETHERNET rings by one or more interconnection points. The
protection switching mechanisms and protocol defined in this recommendation
can be used for a multi-ring/ladder network under the following conditions:
• R-APS channels are not shared across ETHERNET ring connections;
• On each ring port, each traffic channel and each R-APS channel is
controlled (e.g., for blocking or flushing) by the ETHERNET ring
protection control process ("ERP Control Process") of only one
ETHERNET ring.
• Each main ring or sub-ring has its own RPL.
In an ETHERNET ring without congestion with all ETHERNET ring nodes in the
idle state (i.e., no detected failure, no active automatic or external command and
receiving only R-APS (NR, RB) messages) with less than 1,200 km of ring fiber
circumference and fewer than 16 ETHERNET ring nodes, the switch completion
time (transfer time as defined in [ITU-T G.808.1]) for a failure on a ring link shall
be less than 50 ms.
The ring protection architecture relies on the existence of an APS protocol to
coordinate ring protection actions in an ETHERNET ring.
The switch supports up to six rings.
Manual
1.1.0
Enhanced Features 81