CN8236EBGB Mindspeed Technologies, CN8236EBGB Datasheet - Page 71

• Manufacturer Part Number: CN8236EBGB
• Description: ATM SAR 155Mbps 3.3V ABR/CBR/GFR/UBR/VBR 388-Pin BGA
• Manufacturer: Mindspeed Technologies

Specifications of CN8236EBGB

• Package: 388BGA
• Traffic Class: ABR|CBR|GFR|UBR|VBR
• Utopia Type: Level 1|Level 2
• Host Interface: PCI
• Maximum Data Rate: 155 Mbps
• Typical Operating Supply Voltage: 3.3 V
• Minimum Operating Supply Voltage: 3 V

CN8236
ATM ServiceSAR Plus with xBR Traffic Management
3.2.2 Resource Allocation
3.2.3 Resource Isolation
3.2.4 Peer-to-Peer Transfers
28236-DSH-001-B
With either PHY PCI peers, logical peers, or some combination of the two types,
the CN8236 multiplexes each peer’s transmitted packets onto the line and routes
incoming packets to the appropriate peer. The host system allocates shared
resources, such as host and SAR-shared memory, VPI/VCI address space, and
CBR time slots, to peers and clients arbitrarily.
Because each peer is assigned to an independent control and status path, the
CN8236 isolates the resources of each peer. This simplifies resource
management. In addition, queue error conditions caused by a single peer do not
affect any other peers.
The multiple queue architecture of the CN8236 also enables peer-to-peer PCI
transfers. The CN8236 transfers ATM cells as a PCI master. Since the buffer
control structures are independent for each peer, each identifies a unique address
range in PCI memory space. The host defines the address range of each peer. The
CN8236 transfers data within this address range. An address range corresponds
either to a region of centralized host memory, or to a set of peer resident buffers.
memory buffers require store-forward operations, while the peer buffers enable
peer-to-peer transfers. Thus, peer-to-peer transfers reduce the use of the PCI bus.
APPLICATION EXAMPLE
for a Service Access Multiplexer (SAM). The SAM is comprised of the
ATM card and several Frame Relay adapter cards. The host assigns each
Frame Relay adapter card to a set of CN8236 control and status queues at
initialization. During operation, one of the Frame Relay adapter cards
experiences a hardware failure. The failure prevents the card’s processor
from servicing the CN8236’s reassembly status queue. Eventually, the
CN8236 fills the queue and is unable to proceed—this situation is referred
to a queue overflow. The CN8236 shuts down reassembly on VCCs that are
assigned to the overflowed queue only. Since the other cards in the system
are assigned to other status queues, their VCCs remain unaffected by the
failure.
Figure 3-2
A system designer implements a CN8236 terminal as an ATM uplink
Mindspeed Technologies
shows the difference between these two options. Centralized
™
3.2 Multiple Client Architecture
3.0 Host Interface
3-3