Envoy ACP/XF Configuration and Management Manual

WAN Subsystem Profiles and Modifiers for
EnvoyACP/XF
EnvoyACP/XF Configuration and Management Manual—429232-003
3-28
Optional Modifier Descriptions
When NOOPTION1 is enabled and a supervisor station receives an I-frame with the
poll-final bit set, the supervisor immediately sends back an RR-frame with the poll bit
set to acknowledge the received I-frame.
The example in Figure 3-6 assumes two tributary stations (address 01 and address 02)
and shows the NOOPTION1 method of I-frame acknowledgment.
Figure 3-5. OPTION1: Delayed I-Frame Acknowledgment
Note. When OPTION1 is used, the primary station never sends an RR-frame without the
poll/final bit set.
VST017.vsd
The supervisor’s polling cycle is once again at station 01; the supervisor
sends the RR-frame to station 01 with the poll bit set, and the sequence
number for the frame number received (Nr) is increased to 1.
5
Station 02 does not have any information to send, so it responds by
sending the RR-frame with the final bit set.
4
The supervisor station does not immediately acknowledge the I-frame
from station 01, but proceeds to poll tributary station 02.
3
Tributary station 01 responds by sending back an I-frame with the final bit
set.
2
The supervisor station polls tributary station 01 by sending it an RR-frame with
the poll bit set.
1
Legend
01 RR-P
(1)
5
RR-F
4
(0)
02
3
02 RR-P
(0)
2
(0, 0)01 I-F
1
01 RR-P
(0)
(Nr/Ns)
Supervisor Station
Tributary
Stations