R3303-HP HSR6800 Routers High Availability Configuration Guide

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ring contains at least one detected edge, it is called "open ring." If it does not contain any detected
edges, it is called "closed ring."
Data operations on RPR
Stations on an RPR handle data frames by performing the following four types of operations:
• Insert, to place a frame on a ringlet.
• Transit, to pass a frame to the next station.
• Copy, to deliver an inbound frame from the ring to the upper layer. Copying a frame does not
remove the frame from the ring.
• Strip, to remove a frame from a ringlet. The frame is not passed to the next station.
By performing these operations, stations implement unicast, broadcast, multicast, and unknown unicast
transmission.
Unicast transmission
Figure 12 Unicast transmission on an RPR ring
Figure 12 shows how a unicast data frame is transmitted on an RPR ringlet:
1. The source station inserts the unicast frame into the data stream on Ringlet 0 or Ringlet 1.
2. Transit stations transit the frame.
3. The frame is copied and stripped when it reaches the destination station or when its time to live (TTL)
expires.
Different from traditional ring technologies where unicast frames are removed from the ring at the source
station, RPR adopts destination stripping to remove unicast frames from the ring at the destination station.
This increases bandwidth utilization and spatial bandwidth reuse efficiency.
Insert to
ringlet 1
Insert to
ringlet 0
Copy from
ringlet 0
Copy from
ringlet 1
Strip
Transit
Transit