PM7340 S/UNI-IMA-8
PRELIMINARY
INVERSE MULTIPLEXING OVER ATM
DATA SHEET
PMC-2001723
ISSUE 3
INVERSE MULTIPLEXING OVER ATM
12.5.4 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.)
If a group is delete prior to links being deleted, some clean up needs to occur.
The msg bit in the RDAT Sequence memory must be cleared. When clearing this
bit, it must be done using a read modify write procedure to avoid changing the
other reserved fields in that record. Modifying the reserved field may lead to
incorrect operation.
12.5.5 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.
PROPRIETARY AND CONFIDENTIAL TO PMC-SIERRA, INC., AND FOR ITS CUSTOMERS’ INTERNAL USE
276
PMC [ PMC-SIERRA, INC ]
