RS8234EBGC Mindspeed Technologies, RS8234EBGC Datasheet - Page 48

• Manufacturer Part Number: RS8234EBGC
• Description: RS8234EBGC ATM XBR SAR
• Manufacturer: Mindspeed Technologies

2.0 Architecture Overview
2.5 Advanced xBR Traffic Management
2-16
2.5 Advanced xBR Traffic Management
The RS8234 implements ATM’s inherent robust traffic management capabilities
for CBR, VBR, ABR, UBR, GFR and GFC. The RS8234 manages each VCC
independently and dynamically.
• The user assigns each connection a service class, a priority level, and a rate if
• In addition to reserved CBR bandwidth, the RS8234 provides 16
• The host submits data to be sent by writing entries to the transmit queues
• The RS8234 then submits this traffic demand to the xBR Traffic Manager
• The conforming traffic to be transmitted is further groomed in internal
applicable. Then, the on-chip traffic controller, the xBR Traffic Manager,
optimizes usage of the line bandwidth according to the VCC’s traffic
parameters and control information stored in SAR shared memory. The xBR
Traffic Manager guarantees the compliance of each VCC to its service
contract with the ATM network at the UNI ingress point. It schedules all data
traffic by acting as a master to the segmentation coprocessor.
xBR Scheduler. The xBR Traffic Manager assigns segmentation traffic
from active VCCs to schedule ‘slots’, which the segmentation coprocessor
then complies to by segmenting VCC traffic in the sequence/schedule dic-
tated by the xBR Scheduler.
segmentation priorities. The user configures these priorities for the
remaining service categories, including the TM 4.1 defined ABR class.
levels of traffic prioritizing. This is illustrated in
for segmentation. The SAR processes these transmit queues either in round
robin order (transmit queue zero through thirty-one, looped back to zero),
or in priority order (with transmit queue thirty-one having highest
priority). This scheme gives the user or system designer some control of
the delay between the host submitting traffic and the SAR starting to
process that traffic. For instance, the user could assign CBR traffic to the
highest priority transmit queue in order to minimize any delay in
processing and scheduling that traffic.
for scheduling. Traffic is scheduled based on the traffic class plus certain
parameters from the segmentation VCC Table entries (primarily the GCRA
I and L parameters). And if the service category is ABR, the SAR also uses
certain parameters from the ABR templates to help determine that traffic’s
placement on the Schedule Table.
priority queues. Each virtual channel is prioritized according to its
assigned scheduling priority. CBR channels are given pre-assigned
segmentation bandwidth, and channels for the remaining service
categories scheduled according to their priority number (priority zero
being the lowest priority and priority fifteen being highest).
shows this prioritization as a global set of queues, but it is actually
maintained on a per-transmit opportunity basis. In this way, high priority
traffic will be transmitted up to its GCRA limits but will not block lower
priority traffic when idle.
Mindspeed Technologies
One of the functional components of the xBR Traffic Manager is the
The RS8234’s xBR Traffic Manager implements multiple functional
ATM ServiceSAR Plus with xBR Traffic Management
™
Figure
2-9.
28234-DSH-001-B
Figure 2-9
RS8234