User Manual

MDR2400/5800-SR, Orion2410/5810-SRi and Orion 5825-SR
862-01881 Issue 12c Page 122
Only the tributary payload data channels are protected by the redundant link i.e. there
is no protection for Ethernet data. Tributary payload data is split and combined
between links through a 1U protection panel that connects to the user network
equipment as well as the two Digital Indoor Units used at each end of the redundant
link. Although both radio links are functioning continuously, only one of the Digital
Indoor Units is actively driving the tributary channels of the user network at any given
time.
Each Digital Indoor Unit continuously monitors the level of the Packet Error Ratio
(PER) for the radio link on which it is receiving user data. When the PER exceeds a
predefined ratio of 10 consecutive seconds, the Digital Indoor Unit driving the tributary
channels of the user network will signal the redundant Digital Indoor Unit to take over
processing the data it receives over the radio link.
The value of the PER threshold is configurable and can be changed through the Orion
NMS if required. The default value is set at 30%.
There is no notion of a primary and secondary link in this redundancy system. The
first link to be configured successfully will start driving the tributary payload channels.
Switch over will only take place when the aforementioned condition occurs. In the
event where the link to which the data was switched over fails at a later stage, the
system will attempt to switch the data back to the original link.
NOTE 1 A situation can arise where the up- and downstream user tributary data is
carried by separate radio links, i.e. link A carries the upstream data, and link B carries
the downstream data.
NOTE 2 Due to the architecture of the redundancy system, the process of switching
over from one link to another is not hitless and user tributary data will be lost for a few
seconds (< 10)
J.2.2 System Configuration
The block diagram in Figure 10 illustrates a typical redundancy system configuration.
Note that this system is managed over an Ethernet LAN, where the two local Digital
Indoor Units are connected to the LAN using a hub. It is important to note that the IP
addresses for each Digital Indoor Unit should be unique. It is however possible to
configure each link in the redundant system separately through the Element-Manager
port of each local Digital Indoor Unit, in which case it is not necessary to assign unique
IP addresses to the Digital Indoor Units.
The block diagram in Figure 10
also clearly illustrates the following important
interfaces:
• DIU A to DIU B connection through the respective Auxiliary ports of the four
Digital Indoor Units
• The Protection Panel interfaces on each side of the link that combines and splits
the tributary payload channels between the two radio links
• The single user network interfaces provided by the Protection Panel
• The two radio links that provide the redundancy required for user data
protection