S/UNI®-ATLAS-3200 Telecom Standard Product Data Sheet
Preliminary
Acronym
GFC
Definition
Generic Flow Control. At the UNI, a congestion-control flow called GFC is used. The
GFC field occupies the most significant 4 bits of each ATM cell. At the Network-Network
Interface, these 4 bits are used for VPI instead.
Guaranteed Frame Rate. GFR is one of the standard traffic contracts (like CBR, VBR,
and ABR) and is a frame-aware standard supporting AAL5 partial packet discard. S/UNI-
ATLAS-3200 supports GFR policing.
Loopback. Loopback cells are OAM cells used to test the connectivity of the network,
usually during call setup or diagnostics. They are inserted into the network, and looped
back at network nodes based on the content of their loopback location ID. When
loopback cells are first inserted, they are referred to as Parent Loopback cells. Once
looped back (indicated by the Loopback Indication field being zero) they are referred to as
Returned Loopback cells.
GFR
LB
Minimum Cell Rate. MCR is a parameter of Guaranteed Frame Rate (GFR) traffic
contracts. It is analogous to the Sustained Cell Rate (SCR) parameter, but is only
enforced at frame boundaries.
MCR
Network-Network Interface.
NNI
Network Parameter Control. NPC is defined as the set of actions taken by the network
to monitor and control traffic at the Network-Network interface. NPC is what the standards
call policing at an NNI. The main purpose of UPC and NPC is to protect network
resources from malicious as well as unintentional misbehavior, which can affect the QoS
of other already established connections, by detecting violations of negotiated parameters
and taking appropriate actions. Such actions may include cell discard and cell tagging.
NPC
Operations And Maintenance. OAM cells include Fault Management, Performance
Management, Loopback, Activate/Deactivate, and System Administration cells, as well as
other non-standard cells whose VCI or PTI identify them as OAM cells as per ITU-T I.610.
OAM
A Parent, or Forward, Loopback cell. An OAM Loopback cell whose Loopback
Parent LB
PCR
Indication bit is 1, indicating it has not yet been looped back.
Peak Cell Rate. The PCR is a parameter of most traffic contracts, and is enforced by the
policing (UPC/NPC) functions of the device.
PHY
PM
A Physical layer device, or a cell queue associated with a physical-layer interface.
Performance Management. PM is a process whereby cells are transmitted over a VC,
carrying information about the traffic from the point of view of the start point and end point.
From the comparison of the two, statistics about the performance of the connection can
be maintained.
Payload Type Identifier. The PTI is a 3-bit cell field that immediately follows the VCI,
PTI
and is used to identify the cell type for VCCs.
Remote Defect Indication. RDI cells are generated once per second by an OAM end
point, and looped back to be sent in the reverse direction, to indicate that AIS cells have
been received at that end point.
RDI
Rtd LB
Rx Link
A Returned, or Backwards, Loopback cell. An OAM Loopback cell whose Loopback
Indication bit is zero, indicating it has already been looped back.
When configured as an Ingress device, the input of the S/UNI-ATLAS-3200 acts as a Link
Layer device as defined in the UTOPIA Level 3 and POS-PHY3 specs, and connects to a
PHY. This interface is a Master interface in UL3, and a Slave interface in POS-PHY3.
Rx PHY
SCR
When configured as an Ingress device, the output of S/UNI-ATLAS-3200 acts as a PHY
layer device as defined in the UL3 and POS-PHY Level 3 specs, and connects to a TM or
switch that acts as a Link Layer device. This interface is a Slave interface for UL3, and a
Master interface for POS-PHY Level 3.
Sustained Cell Rate. The sustained cell rate is a parameter of some traffic contracts,
and indicates the maximum throughput that may be sustained over a long period of time.
Proprietary and Confidential to PMC-Sierra, Inc., and for its Customers’ Internal Use
Document ID: PMC-1990553, Issue 4
23
PMC [ PMC-SIERRA, INC ]
