S/UNI-IMA-4 Telecom Standard Product Data Sheet
Released
Rate Changes
When the RIPP changes the state of a link to active, it programs the appropriate IDCC scheduler
with the new rate. This is done by providing a vector that identifies the active LIDs for the
group. This vector is used to determine the number of links for the rate calculation and is then
passed on to the TIMA or RDAT to indicate the LIDs to include in the round robin. The IDCC
will only change its rate at IMA frame boundaries.
10.2.6 Support of IMA Test Pattern Procedure
S/UNI-IMA-4 supports the IMA test pattern procedure in both the TX direction (NE initiated)
and RX direction (FE initiated).
In the TX direction, the S/UNI-IMA-4 updates the TX test control info and TX test pattern field
in the outgoing ICP cells, as prompted by the relevant Update_test_ptn command. PM must
take care to wait at least 2 frames in between updates to the test pattern in order to comply with
the IMA test pattern standard. Meanwhile, the S/UNI-IMA-4 will always compare the RX test
pattern field received in the incoming ICP cells with the TX test pattern value being transmitted,
and save the result on a per-link basis in the group context memory.
In the RX direction, the S/UNI-IMA-4 always analyzes the TX test control info field in the
incoming ICP cells. If the test link command field is set to “active”, the TX test pattern field in
the incoming ICP cells on the selected link will be copied to the RX test pattern field in the
outgoing ICP cells. Otherwise the RX test pattern field in the outgoing ICP cells will be filled
with “0xFF”.
10.2.7 Support of Symmetric/Asymmetric Operation Modes
S/UNI-IMA-4 supports all three possible group symmetry modes: symmetric configuration and
symmetric operation; symmetric configuration and asymmetric operation; asymmetric
configuration and asymmetric operation.
For symmetric configuration, the number of TX and RX links in the group must be the same;
for asymmetric configuration, that restriction does not apply.
The support for asymmetric/symmetric operation modes is part of the S/UNI-IMA functionality.
The symmetric operation mode is treated as a special case of the asymmetric operation, where
the TX and RX LSM on the same physical link are inter-dependent.
10.2.8 Support of Different IMA Versions
It should be noted that the technique used to report RX information over the Link Information
fields in the ICP cells when the group is configured in the symmetrical configuration and
operation mode differs in the IMA v1.1 implementations and the IMA v1.0 implementations.
The details of the differences between IMA v1.1 and IMA v1.0 can be found in appendix C of
the ATM Forum IMA 1.1 specification.
Proprietary and Confidential to PMC-Sierra, Inc., and for its customers’ internal use.
Document No.: PMC-2020889, Issue 2
78
PMC [ PMC-SIERRA, INC ]
