Edge-Core ECS4120-28F, Reference Manual, Page: 533 / 938

Chapter 20
| ERPS Commands
– 533 –
non-erps-dev-protect
This command sends non-standard health-check packets when an owner node
enters protection state without any link down event having been detected through
SF messages. Use the
no form to disable this feature.
Syntax
[ no ] non-erps-dev-protect
Default Setting
Disabled
Command Mode
ERPS Configuration
Command Usage
◆
The RPL owner node detects a failed link when it receives R-APS (SF - signal
fault) messages from nodes adjacent to the failed link. The owner then enters
protection state by unblocking the RPL. However, using this standard recovery
procedure may cause a non-EPRS device to become isolated when the ERPS
device adjacent to it detects a continuity check message (CCM) loss event and
blocks the link between the non-ERPS device and ERPS device.
CCMs are propagated by the Connectivity Fault Management (CFM) protocol as
described under
“CFM Commands” on page 773 . If the standard recovery
procedure were used as shown in the following figure, and node E detected
CCM loss, it would send an R-APS (SF) message to the RPL owner and block the
link to node D, isolating that non-ERPS device.
Figure 3: Non-ERPS Device Protection
When non-ERPS device protection is enabled on the ring, the ring ports on the
RPL owner node and non-owner nodes will not be blocked when signal loss is
detected by CCM loss events.
◆
When non-ERPS device protection is enabled on an RPL owner node, it will
send non-standard health-check packets to poll the ring health when it enters
the protection state. It does not use the normal procedure of waiting to receive
an R-APS (NR - no request) message from nodes adjacent to the recovered link.
Instead, it waits to see if the non-standard health-check packets loop back. If
they do, indicating that the fault has been resolved, the RPL will be blocked.
After blocking the RPL, the owner node will still transmit an R-APS (NR, RB - ring
blocked) message. ERPS-compliant nodes receiving this message flush their
forwarding database and unblock previously blocked ports. The ring is now
returned to Idle state.
non-ERPS
A
non-ERPS
RPL
Owner
RPL
X X
blocked blocked
fault
B C D E F