Cisco 15327 - Manual (Page 257)

17-5
Ethernet Card Software Feature and Configuration Guide, R7.2
Chapter 17 Configuring Cisco Proprietary Resilient Packet Ring
Cisco Proprietary RPR Framing Process
Cisco Proprietary RPR Framing Process
Cisco proprietary RPR on the ML-Series card uses a proprietary RPR frame and high-level data link
control (HDLC) or GFP-F framing. It attaches the Cisco proprietary RPR frame header to each Ethernet
frame and encapsulates the Cisco proprietary RPR frame into the SONET/SDH payload for transport
over the SONET/SDH topology. the Cisco proprietary RPR header is removed at the egress ML-Series
card.
Figure 17-3 illustrates the Cisco proprietary RPR frame.
Figure 17-3 Cisco Proprietary RPR Frame for ML-Series Card
The Cisco proprietary RPR framing and header includes a number of fields, including four bytes for
source and destination station information and another four bytes for control and quality of service
(QoS).
Figure 17-4 illustrates the Cisco proprietary RPR frame format. Table 17-1 defines the most
important fields.
134984
Flag Add Control Protocol
0x7E 0x0F 0x00 0x0042
1 byte 1 byte
CRC Flag
0x7F
2-4 bytes 1 byte
FCS
4 bytes
1 byte 2 bytes
RPR Payload
68-1522 bytes
RPR Address RPR Control
4 byte 4 bytes
Ethernet Payload
60-1514 bytes
Preamble SFD
7 byte 1 byte
DA
6 bytes
SA
6 bytes
Ln/Type
6 bytes
Data/Pad
46-1500 bytes