
Industrial Managed
Ethernet Switch
User Manual
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2.15 ERPS Ring
E
thernet
R
ing
P
rotection
S
witching (
ERPS
) is a protocol for Ethernet layer network rings
.
The protocol specifies the
protection mechanism for sub
-
50ms delay time
.
The ring topology provides multipoint connectivity economically by
reducing the number of links. ERPS provides highly reliable and stable protection in the ring topology, and it never
forms loops, which can affect network operation and service availability. Figure 2.141 depicts an example of ring
topology forming by four Atop
’s managed switch EH75XX series
.
Figure 2.141 An Example of Ring Topology (Example made on EH7520)
Figure 2.141 shows that each Ethernet Ring Node is connected to its adjacent Ethernet Ring Nodes participating
in the same Ethernet Ring using two independent links (i.e. two ways). In the Ethernet ring, loops can be avoided
by guaranteeing that traffic may flow on all but one of the ring links at any time
.
This particular link is called Ring
Protection Link (RPL). A control message called Ring Automatic Protection Switch (R-APS) coordinates the
activities of switching on/off the RPL. Under normal conditions, this link is blocked by the Owner Node. Thus, loops
can be avoided by this mechanism. In case an Ethernet ring failure occurs, one designated Ethernet Ring Node
called the RPL Owner Node will be responsible for unblocking its end of the RPL to allow RPL to be used as a
backup link
.
The RPL is the backup link when one link failure occurs
.
Atop
’s EH75XX series industrial managed switches provide a number of Ethernet ring protocol
.
The
ERPS
/
Ring
section is subdivided into five menus as shown in Figure 2.142, which are
:
ERPS Setting
,
iA
-
Ring Setting
,
C
-
Ring
Setting
,
U
-
Ring Setting
,
Compatible
-
Chain Setting
and
MRP
(Media Redundancy Protocol)
.