?– The minimum frame size is 16 bytes.
?– The maximum frame size is 9216 bytes.
?– Auto-negotiation is not used.
?– Flow control is disabled.
?– Remote fault is not generated by the transmitter and if present is ignored by the
receiver.
Figure 12.20 Fairness and idle frame formats
Fairness frame format
ttl
base control
sa control
fairness header
fair rate
fcs
Covered by FCS
Covered by FCS
Idle frame format
ttl
base control
sa control
idle payload = all 0
fcs
1
1
6
2
2
4
1
1
6
4
4
354 Chapter 12
SONET/SDH PHYs RPR can be mapped to SONET/SDH through three types of adaptation
sublayers:
?– GFP
?– HDLC-like
?– LAPS
Frame-mapped GFP framing for RPR complies with ITU-T G.7041 using a null extension
header as defined by the extension header identifier (EXI), no GFP FCS field,
and with a user payload identifier (UPI) corresponding to an RPR payload.
Byte-synchronous HDLC-like framing for RPR complies with IETF RFC 1662 using
byte-stuffed framing, with references to PPP frames to be interpreted as RPR frames.
Instead of using LCP for link negotiation, byte-synchronous HDLC-like framing for
RPR uses the following statically-defined link parameters:
?– Address and Control Field compression is always used.
Pages:
778
779
780
781
782
783
784
785
786
787
788
789
790
791
792
793
794
795
796
797
798
799
800
801
802