S/UNI-IMA-4 Telecom Standard Product Data Sheet
Released
13.5.4 Deleting a Group
There are two methods of bringing a group down. To bring a group down and preserve data that
has already been transmitted, it is recommended that the links be deleted first using the
Delete_link command. This will result in the GSM transitioning to the insufficient links state
when the number of active links falls below the minimum required links. Once the delete links
is complete and all of the accumulated DCB data is played out, the Delete_group command
deletes the existing group. To determine if the deleted links have all of the DCB data played
out, the TX_LINK_EN and RX_LINK_EN bits may be polled in the RIPP Link Context
records. Once the Delete_group command is executed, all links within the group will
immediately stop transmitting IMA frames, and all received cells queued in the DCB buffer will
be dropped.
If data preservation is not a concern, a group may be removed immediately by issuing the
Delete_group command. It is recommended that interrupts be disabled prior to the group
deletion since the group deletion itself causes an interrupt to occur. If a Read_event command
is issued on a deleted group, the command will be rejected. If interrupts are not disabled, care
must be taken to ensure proper servicing of the RIPP Interrupt FIFO prior to reusing the group
to avoid overrunning the RIPP Interrupt FIFO (interrupt from group prior to deletion and
interrupt from group after re-use both in FIFO, and the FIFO is sized to have a maximum of one
event per group.)
13.5.5 Restart Group
To restart a group or issue a local reset to a group, the Restart_group command is used. Upon a
Restart_group, the specified group’s GSM will immediately transition to the Start-up state and
try to renegotiate the IMA parameters. This command should be used after changing the M
values, IMA ID, group symmetry, or OAM value on a group.
13.5.6 Inhibit Group/Not inhibit Group
To move a GSM into/out of the Blocked state, the Inhibit_group and Not_inhibit_group
commands may be used. These commands set a mode such that the current GSM state is not
important. Once set to the inhibit mode, the GSM will go to the Blocked state instead of the
Operational state. The Not_inhibit_group command must be executed to remove this setting.
13.5.7 Adding a link or Links to an existing Group (Start LASR)
In order to add links to an existing group, the START_LASR command is used. Prior to issuing
this command, the RX_LINK_EN bits and TX_LINK_EN bits in the RIPP Link Context should
be checked to make sure they are zero (this indicates that, if these links were previously in
another group, the previous delete link operation is complete). Then, the link configuration
should be performed as in 0. The Start_LASR command will initiate the Link Addition and
Slow Recovery Procedure. The LASR procedure is paced by either (1) all of the indicated
links’ LSM’s transitioning to the appropriate states or (2) the programmed link timeouts in the
presence of defective or slow links.
The LASR procedure continues after the CMD_ACK is returned. While a LASR procedure is
in process, no other LASR procedure may be started on the same group.
Proprietary and Confidential to PMC-Sierra, Inc., and for its customers’ internal use.
Document No.: PMC-2020889, Issue 2
283
PMC [ PMC-SIERRA, INC ]
