Edge-Core ECS4120-28F, Reference Manual, Page: 546 / 938

Chapter 20
| ERPS Commands
– 546 –
Example
Console#erps clear domain r&d
Console#
erps forced-switch
This command blocks the specified ring port.
Syntax
erps forced-switch [ domain ring-name ] { east | west }
ring-name - Name of a specific ERPS ring. (Range: 1-12 characters)
east - East ring port.
west - West ring port.
Command Mode
Privileged Exec
Command Usage
◆
A ring with no pending request has a logical topology with the traffic channel
blocked at the RPL and unblocked on all other ring links. In this situation, the
erps forced-switch command triggers protection switching as follows:
a.
The ring node where a forced switch command was issued blocks the traffic
channel and R-APS channel on the ring port to which the command was
issued, and unblocks the other ring port.
b.
The ring node where the forced switch command was issued transmits R-
APS messages indicating FS over both ring ports. R-APS (FS) messages are
continuously transmitted by this ring node while the local FS command is
the ring node’s highest priority command (see
Table 101 on page 547 ). The
R-APS (FS) message informs other ring nodes of the FS command and that
the traffic channel is blocked on one ring port.
c.
A ring node accepting an R-APS (FS) message, without any local higher
priority requests unblocks any blocked ring port. This action subsequently
unblocks the traffic channel over the RPL.
d.
The ring node accepting an R-APS (FS) message, without any local higher
priority requests stops transmission of R-APS messages.
e.
The ring node receiving an R-APS (FS) message flushes its FDB.
◆
Protection switching on a forced switch request is completed when the above
actions are performed by each ring node. At this point, traffic flows around the
ring are resumed. From this point on the following rules apply regarding
processing of further forced switch commands: