TAAD08JU2 Datasheet, PDF (90/174 Pages) Agere Systems – T1/E1/J1 ATM Processor, Versions 2.1 and 3.1

TAAD08JU2
T1/E1/J1 ATM Processor, Versions 2.1 and 3.1
Data Sheet
August 18, 2003
17 ATM Port Controller (APC) Block (continued)
! Provides OAM fault management functions for loopback, continuity check, defect indication on all connections,
and performance monitoring for up to 127 processes.
! Provides an enhanced services interface (ESI) to support operation of an optional external adjunct device for
comprehensive statistical data collection and virtual source/virtual destination (VS/VD) ABR functionality sup-
port.
! Queues up to 4096 cells in on-chip memory.
17.4 Summary of Commands
The commands associated with the APC block fall into the following categories:
! Initialization: used only at device initialization to set modes, enable features, configure ports, and set identifier
ranges and scheduler limits.
! Configuration: used to configure the schedulers at initialization and dynamically.
! Masks: masks alarm interrupts and statistics reporting.
! Connection: used to set up and tear down individual connections and set their associated parameters, statistics
gathering, fault state, and OAM behavior.
! Cell insertion: used to insert cells onto bidirectional connections.
! Statistics: used to retrieve global or per-connection statistics.
17.5 Buffer Management
The following buffer management thresholds exist in the APC:
! CLP1 discard threshold
! CLP0+1 discard threshold
! Partial packet discard (PPD)
! Early packet discard (EPD) threshold
! Selective EFCI (SEFCI) marking threshold
! Ingress fabric backpressure (IFBP) alarm threshold
These thresholds, with the exception of SEFCI and IFBP, are dynamic and provided per-VC for each traffic class.
Except for IFBP, which exists only on the ingress, all other thresholds are provided both on the ingress and egress
sides. Furthermore, SEFCI and IFBP are provided per-port, per-traffic-class on the ingress, and per-subport and
per-traffic-class on the egress.
The per-VC thresholds are dynamic because they change depending on the amount of free buffer space available.
The larger the free buffer space, the higher the threshold. The APC provides the option to configure the per-VC
dynamic thresholds as static thresholds, as well as the capability to partition the buffer space between the five traf-
fic classes. Thus, there is flexibility for using the buffer space differently for different traffic classes. For example,
large buffers can be used for nrt-VBR traffic class, implying smaller effective bandwidths for given traffic descrip-
tors. For CBR and rt-VBR traffic classes, CDV and CTD constraints dictate smaller buffer requirements.
The APC also provides the facility to limit the buffer usage per-port, per-traffic-class on the ingress, and per-sub-
port and per-traffic-class on the egress. The APC buffer management scheme makes use of the concepts of effec-
tive scheduling bandwidths and buffer allocations to guarantee (to a given statistical probability) delay and cell loss
ratios for connections admitted on the condition of their conformance to leak-bucket traffic regulation, and it pro-
vides those effective bandwidth and buffer values on a per-VC basis within the VC parameter table entry.
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