
Chapter 4: Feature Description
Innovative Techniques to Boost Capacity and Reduce
Latency
External Protection
1+1 HSB protection utilizes two PTP 820S units with a single antenna, to provide hardware
redundancy for Ethernet traffic. One PTP 820S operates in active mode and the other operates in
standby mode. If a protection switchover occurs, the roles are switched. The active unit goes into
standby mode and the standby unit goes into active mode.
The standby unit is managed by the active unit. The standby unit mutes its transmitter, but the
standby unit’s receiver is kept on in order to monitor the link. However, the received signal is
terminated at the switch level.
Port 1 on each PTP 820S is connected to an external switch or an optical splitter. Both ports on
each PTP 820S unit belong to a LAG, with 100% distribution to port 1 of the respective PTP 820S
unit.
If traffic is routed to the PTP 820S units via an external switch, the switch is configured as a static
LAG. This is called Line Protection mode. In Line Protection mode, Port 2 on each PTP 820S is
connected to Port 2 of the other PTP 820S. The traffic to the standby unit is forwarded to the active
unit via Port 2 of each unit. This enables the active unit to monitor traffic to the standby unit.
Figure 14 1+1 HSB Protection – Line Protection Mode
Alternatively, an optical splitter can be used to route traffic to the interfaces on each PTP 820S unit
called Split Protection mode. No protection forwarding cable is required in Split Protection mode.
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