S/UNI®-ATLAS-3200 Telecom Standard Product Data Sheet
Preliminary
The tags (3) and (4) indicate the second bi-directional PM flow. At the Ingress S/UNI-ATLAS-
3200, the Cell Processor generates a Forward Monitoring Cell that is transmitted to the Output
Cell Interface (and into the Switch Fabric). A downstream device (e.g. another ATLAS device)
would terminate the Forward Monitoring PM cell and generate a Backward Reporting PM cell.
This Backward Reporting PM cell is received at the Egress S/UNI-ATLAS-3200 and terminated
in its Cell Processor. This is the first half of the bi-directional flow, indicated by (3). The second
half of the bi-directional flow is indicated by (4). Here, the Egress S/UNI-ATLAS-3200
terminates a Forward Monitoring PM cell. The Egress S/UNI-ATLAS-3200 then generates a
corresponding Backward Reporting PM cell which is transmitted to the Ingress S/UNI-ATLAS-
3200 through the Backward Cell Interface and back into the switch core. The generation of the
Forward Monitoring PM cell (4) would be maintained by the Ingress S/UNI-ATLAS-3200 in one
RAM location. The termination of the Forward Monitoring PM cell (4) and the statistics
collected from the termination of the Backwards Reporting PM cell (3) would be maintained by
the Egress S/UNI-ATLAS-3200 in one RAM location.
The above discussion is just one example of the PM Flow capability of the S/UNI-ATLAS-3200.
Each of the PM flows can be configured as a monitoring point in which PM cells are neither
generated nor terminated (note, however, PM cells will be terminated at OAM flow end points),
but merely monitored and their statistics maintained. The S/UNI-ATLAS-3200 can also be
configured to monitor/sink/source an F4 PM flow. Each F5 connection that is a member of an F4
VPC flow must have one common PM Address for the F4 flow. All user cells (at the F4 level)
will be considered to be part of the F4 PM flow, and thus counted as such.
A pair of S/UNI-ATLAS-3200s can also be configured to perform bi-directional PM on a segment
connection and an end-to-end connection (simultaneously) for up to 256 bidirectional connections
simultaneously. For each connection in each S/UNI-ATLAS-3200, one PM address in the VC
Linkage Table would be used to point to the PM RAM location for the end-to-end PM flow, and
the other address would be used to point to the PM RAM location for the segment PM flow. The
Backwards Cell Interfaces of the two devices permit Backwards PM cells to be inserted into the
opposite direction.
The insertion of Forward Monitoring PM Cells is controlled by the Paced Forward PM Cell
Generation registers. These registers provide a counter to set the number of cell intervals
(defined as 22 SYSCLK clock cycles) between successive Forward Monitoring PM cells. This
prevents the S/UNI-ATLAS-3200 from generating Forward Monitoring PM cells back-to-back.
Each time a Forward Monitoring PM cell is generated, a counter is loaded with the value set in
the Paced Fwd PM Cell Generation register, and that register is decremented at intervals of 32
clock cycles. Another Forward Monitoring cell will not be generated until the counter reaches 0.
The position of the UPC/NPC policing needs to be clearly defined. If the S/UNI-ATLAS-3200 is
a sink of Forward Monitoring PM cells, or a monitoring point, the counts maintained in the PM
RAM represent the state of the device before the UPC/NPC function. If the S/UNI-ATLAS-3200
is a source of Forward Monitoring PM cells, the counts maintained in the PM RAM represent the
state of the device after the UPC/NPC function.
Proprietary and Confidential to PMC-Sierra, Inc., and for its Customers’ Internal Use
Document ID: PMC-1990553, Issue 4
120
PMC [ PMC-SIERRA, INC ]
