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Horizon Compact Release 1.01.00 Wireless Ethernet Product User Manual – Volume 2
being sent over the Horizon link. This continuous data stream is used as the trigger for Protection
Switching activation. Therefore, it is able to detect both hardware failures as well as link failures.
Switching times are in the order of 50 msec.
3.12.4 Recovery After Protection Switching
After a redundancy switch has occurred, return to the original path is achieved with a manual override. If,
however, the path has been switched from previously active to stand-by, then, if a link failure or outage
on the stand-by path occurs the data path will automatically switch back (reverting) to the previously
active path, provided that the system parameters have been set to allow the switch back.
3.12.5 Forcing the Data Path to a Particular Link
It is possible to force the activity to follow a particular path. This option can be used during regular
operation of the link, or it can be used as a trouble-shooting tool. The CLI command is set redundancy
override [primary/secondary/manual/auto]. Selecting “primary” will force the path onto the link being
supported by the Horizon unit configured as the primary. Selecting “secondary” will force the path onto
the link being supported by the Horizon unit configured as the secondary. In either case, activity will
remain with the selected unit, regardless of path conditions, until the user issues another relevant
command.
3.12.6 Redundancy CLI Commands
Redundancy Mode:
The redundancy mode is set for both the units at each end. Set the appropriate units as either primary or
secondary and set the appropriate mode of 1-wire or 2-wire. This command is to be issued on all 4 units.
Command syntax: get/set redundancy mode [primary_hsb_1wire | secondary_hsb_1wire |
primary_hsb_2wire | secondary_hsb_2wire| off]
Note : (hsb = hot stand-by)
Redundancy Override
The options for redundancy override are primary, secondary, manual, auto, none. Selecting “primary” will
force the Horizon unit configured as “primary” to carry the traffic and it will remain there. Traffic will not be
switched to the stand-by link, even if the active link fails. Similarly, selecting “secondary” will force the
Horizon unit configured as the secondary to carry the traffic and it will not switch away from that unit.
Selecting “manual” and “auto” has a different affect depending on if the systems are configured as 1-wire
or 2-wire installations.
1-Wire configuration
“Auto” is not supported for the 1-wire mode. Selecting “auto” defaults to the “manual” behaviour
as follows: On power-up, the Horizon unit that is configured as the primary unit instructs the
secondary unit to attempt to establish a link with its peer at the far end. If successful, this link
becomes the active link and the primary Horizon remains in stand-by. If the secondary unit cannot
establish a link, then the system returns activity to the primary unit, where it remains, regardless
as to if it can establish a viable link or not. The primary unit controls this operation.
2-Wire configuration
In the “manual” option, on power-up, whichever Horizon units (primary or secondary) can
establish a link, they will take control and remain as the active link. If they cannot establish a link,
then they give up control to the other unit and remain in stand-by unless manually switched.
Selecting “auto” will result in the activity toggling between the secondary and primary units in
order to find a suitable link. If the secondary unit cannot establish a link then activity will switch to
the primary unit. If the primary unit cannot establish a link, then activity will switch back to the
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