26-5
Ethernet Card Software Feature and Configuration Guide, R7.2
January 2009
Chapter 26 Configuring IEEE 802.17b Resilient Packet Ring
RPR-IEEE Framing Process
Figure 26-3 illustrates the RPR-IEEE topology and protection control frame. Topology and protection
(TP) frames are usually sent to the broadcast address.
Figure 26-3 Topology and Protection Control Frame Formats
Figure 26-4 illustrates the RPR-IEEE fairness frame. Fairness frames are sent either to all stations or
only the nearest neighbor depending on whether it is a single-cho ke fairness frame (SCFF) or
multi-choke fairness frame (MCFF). Fairness frames are included in the total bandwidth of the QoS A0
service class. This eliminates the need for a destination address (DA). The MCFF type also includes an
additional frequency division duplexing (FDD) frame to help smooth the fairness variation. Th e field SA
Compact is the address of the station providing the fair rate.
Note The ML-Series card supports multi-choke fairness frames from other stations on the RPR-IEEE. The
ML-Series card does not generate these frames.
151967
Payload
Trailer
Control Version1
FCS
Control Data Unitn
4
Control Type1
1TTL to Dest
Base Control
MAC da
TTL Base
MAC sa
Extended Control
hec
6
1
1
6
1
2
Header