S/UNI-IMA-4 Telecom Standard Product Data Sheet
Released
To minimize the effect on the group traffic rate, while the delay is being reduced, the ATM cells
from the group will be transferred to the ATM layer at a rate of (1+1/16)*IDCR versus IDCR.
In other words, the group will playout data 6.25% faster to the ATM layer during the process of
delay reduction.
The amount of time the delay removal takes depends upon the amount of delay to be removed.
For example, a group where 200 ms of delay is to be removed takes approximately 3 seconds
for the process to complete.
While delay adjustments are being made to a group, new links cannot be added and links cannot
be recovered from an error state. The S/UNI-IMA-4 will reject any requests to start a LASR
procedure. However, while delay adjustments are in progress, links can be deleted or made
unusable.
Group Start-up Procedure
When the Add_Group Command is issued, the Group state machine will enter the start-up state
and start to send IMA frames on the configured Tx links.
Start-up State
While in the start-up state, the configured TX link state machines will be reporting the Unusable
state and the rx-link state machines will be reporting Not_In_Group. At this point, the S/UNI-
IMA-4 will start to monitor the incoming ICP cells. When ICP cells are received with the FE
indicating that the Group is in Start-up, the S/UNI-IMA-4 will transition to the Start-up-Ack
state if the M value, the Group Symmetry, the OAM Label and IMA_ID (optional) values are
acceptable. Otherwise, the S/UNI-IMA-4 will transition into the Config-Aborted State.
Config-Aborted State
When entering the Config-Aborted State, a timer is started and an interrupt is generated. The
S/UNI-IMA-4 will stay in the config-aborted state until either:
The management plane restarts the group using the Restart_Group Command. The restart can be
done with either the same parameters or with different parameters.
The config-abort timeout expires.
Start-up-Ack State
When entering the Start-up-Ack State, a timer is started. In the Start-up-Ack state, the S/UNI-
IMA-4 waits for the FE to report the Start_Up_Ack state. If the timer expires prior to the FE-
reporting Start_Up_Ack (or insufficient links, blocked, or operational states), the S/UNI-IMA-4
transitions back into the Start_Up state. Otherwise, when the FE reports Start-up-Ack, the
S/UNI-IMA-4 transitions to the Insufficient Links state.
Proprietary and Confidential to PMC-Sierra, Inc., and for its customers’ internal use.
Document No.: PMC-2020889, Issue 2
75
PMC [ PMC-SIERRA, INC ]
