Cisco 15327 - Manual (Page 437)

26-5
Ethernet Card Software Feature and Configuration Guide, R7.2
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-choke 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. The 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 Version 1
FCS
Control Data Unit n
4
Control Type 1
1 TTL to Dest
Base Control
MAC da
TTL Base
MAC sa
Extended Control
hec
6
1
1
6
1
2
Header