
PRELIMINARY
INVERSE MULTIPLEXING OVER ATM
PM7341 S/UNI-IMA-84
DATASHEET
PMC-2000223
ISSUE 4
INVERSE MULTIPLEXING OVER ATM
PROPRIETARY AND CONFIDENTIAL TO PMC-SIERRA, INC., AND FOR ITS CUSTOMERS’ INTERNAL USE
372
DIFF_DELAY_INT
INVALID_ICP_INT
RX_TIMEOUT_INT
TX_TIMEOUT_INT
In order to track the progress of the command, interrupts may be enabled for
GSM state changes and for the LSM state changes for all of the links. This may
result in a large number of events if the group includes a large number of links.
NOTE: If the TRL link is not validated on the RX side, since the group does not
have a valid TRL, the group will not come up and will not report any events. If
this happens, a Restart_group command must be executed to recover.
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.)
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