S/UNI-IMA-4 Telecom Standard Product Data Sheet
Released
Rx Links
During the LASR procedure, the LIDs for the receive links are validated. Until the LIDS are
validated, the RX Links report the “Not in Group” state. As the LIDS are validated, the Rx
Links start to report the unusable state. This transition is not synchronized with other links in the
group.
After all the receive links have their differential delay checked and have no defects (obtained
IMA Frame sync) or a programmable timeout occurs, all of the accepted links will transition to
the usable state.
After the Rx links are reported usable, another programmable timeout is started. Once all of the
links are reported TX Usable by the FE or the timeout expires, the accepted links will start to
report RX_Active. If operating in symmetrical mode, the NE TX links must be in the
usable/Active state in order for the accepted links to transition into RX_Active. If some
additional links have become usable since the last timeout, they will skip directly from the
unusable to the active state.
This completes the LASR for the Rx Links. When the LASR for both the RX and TX links is
complete, the LASR procedure is complete. If the LASR completes due to a timeout and not all
of the links are in the active state, an interrupt will be generated (if enabled) to inform PM that
the links were not brought to the active state.
Deactivating Links
Links may be brought down by either PM or by the far end. PM may declare a fault on a link,
inhibit a link, or delete the link. The Far-end state changes may also cause the link to go down.
This is the method of coordinating link deactivation between the NE and FE.
Far End link deactivation
If the FE Tx states transition into an unusable state, the NE Rx states go to the usable state and
all data received prior to this point will be played out.
If the FE Rx states transition into a not active state, the NE TX link will transition into the
usable state and stop transmitting data on that link.
Near End (management) link deactivation
If the NE Rx link is removed from the group, the S/UNI-IMA-4 will transition to the deleted
state until all previously received data is played out to the ATM layer; at which point, it will
deactivate itself and be removed from the round-robin.
In absence of defects, the S/UNI-IMA-4 will bring down the link without loss of data.
Proprietary and Confidential to PMC-Sierra, Inc., and for its customers’ internal use.
Document No.: PMC-2020889, Issue 2
77
PMC [ PMC-SIERRA, INC ]
