S/UNI®-ATLAS-3200 Telecom Standard Product Data Sheet
Preliminary
10.9.5 Automated Protection Switching Cells
APS Coordination Protocol cells are identified with an OAM Cell Type of 0101. They are
handled like other OAM cells, and can be copied to the MCIF via the APStoUP bit in the
Configuration field of the VC Table, or to the BCIF via the combination of the per-VC APStoUP
bit and the APStoBCIF bit in the Routing Configuration Register. They are identified by a code in
the Cell Type field of the Microprocessor Cell Info field and the BCIF Cell Info Field. APS CP
cells may be passed on to the OCIF at OAM end-points by setting the APStoOCIF bit to logic 1
in the Routing Configuration Register.
10.9.6 Resource Management Cells
Resource Management (RM) cells are identified by a PTI=110 for VC-RM cells and by VCI=6
for VP-RM cells. As a programmable option, VP-RM cells can be further qualified by PTI=110.
The S/UNI-ATLAS-3200 does not process the RM cell payload, but simply passes these cells to
the Output Cell Interface with an optionally translated header. As a programmable option, the
S/UNI-ATLAS-3200 can copy RM cells to the Microprocessor Cell Interface.
10.10 F4 to F5 OAM Processing
The S/UNI-ATLAS-3200 supports the termination of F4 (VPCs) to F5 (VCCs) while maintaining
the F4 to F5 transmission of OAM cells. Each VCC of a VPC must be setup as a separate
connection in the VC Table. An additional connection must be set up for the F4 OAM flow. The
search table must be set up so that both Segment OAM cells (VCI=3) and End-to-End OAM cells
(VCI=4) of the VPC resolve to this F4 OAM connection, but the VCI field in its VC Table must
be set to all-zeroes to indicate that it is to be handled like an F4 connection. The F4 OAM
connection may be set up as both a segment and end-to-end point, or as an end-to-end-point only.
The VCC connections have a VPC Pointer [16:0] and a VPC Pointer Active bit in the Linkage
Table. The pointer must be configured to point to the F4 OAM connection. Note that the two
least significant bits of the VPC Pointer (i.e. the VCRA of the F4 OAM connection) must be
different from the two LSBs of any of its associated VCC connections. Failure to adhere to this
rule will result in all the VCC connections being treated as inactive until the problem is resolved.
If the VPC pointer of a connection is not used, then the VPC Pointer Active bit must be set to
logic 0. If a segment or end-to-end AIS alarm condition is indicated on the VPC connection, a
background process ensures that VCC AIS cells will be transmitted on all VCCs associated with
that VPC, while the VPC is in AIS alarm condition.
The Continuity Check process is also active at the F4 and F5 levels. When a user cell or CC cell
is received on a VCC, the VPC connection is updated to ensure it does not enter the CC Alarm
state.
The figure below illustrates how the S/UNI-ATLAS-3200 supports OAM flows when terminating
VPC connections. Note that each VCC connection has its VPC pointer pointing to the F4 OAM
connection. The F4 OAM connection’s VPC pointer active bit must be set to logic 0, and its VPC
pointer field is not used.
Proprietary and Confidential to PMC-Sierra, Inc., and for its Customers’ Internal Use
Document ID: PMC-1990553, Issue 4
108
PMC [ PMC-SIERRA, INC ]
