ibm3206k0424 ETC-unknow, ibm3206k0424 Datasheet - Page 277

• Manufacturer Part Number: ibm3206k0424
• Description: Ibm Processor For Network Resources
• Manufacturer: ETC-unknow

Preliminary
Timeline Example of Frame Scheduling
The above example assumes that one slot time is initialized to the time it takes to send 64 bytes out on the
line. The term "cells" was used in this example to mean a 64-byte block of packet data. In frame mode, the
ATM header is not prepended to the data being sent.
Weighted fair queueing on a frame basis is supported on the low priority queue by setting bit 17 in the CSKED
Control Register. When using frame-based scheduling and weighted fair queuing together, the average inter-
val will be used to limit the spacing between packets, not cells.
Path Scheduling
CSKED has logic to support sharing scheduling parameters between multiple connections. In path schedul-
ing, an LPD is set up to contain the scheduling parameters for the group of connections in the same way it is
done for LCDs. All connections that wish to share this bandwidth set the alter_sched field in their LCD to
indicate this VC is on a VP, and initialize the lpd_pointer field to point to the LPD. The segmentation portion of
the LPD is not used since the segmentation parameters are taken from the LCD. The scheduling parameters
in the LCDs are not used as they are in the LPD. The bandwidth is shared on a packet or cell basis depending
the value of the alter_sched field in the LCD. Since both the LPD and LCD need to be fetched for each trans-
mit opportunity, this scheduling method should not be used where the performance boundaries are being
pushed, as in 622 Mbps. See Transmit Logical Channel Descriptor Data Structures on page 66 for further
information on LPD descriptors.
Primitives
Enqueue
After a packet has been written to memory and the packet header updated with the offset and length of the
data and the LCD address of the connection, an enqueue primitive needs to be issued to the Transmit
Enqueue Primitive address.
Close Connection
When no more traffic is to be sent on a connection, this primitive can be executed to cause an event to be
generated when segmentation has stopped on this connection. Segmentation will be stopped immediately, or
stopped after all packets on this connection have been transmitted as specified in the CSKED Control Regis-
ter.
pnr25.chapt05.01
August 14, 2000
|<----------------------------->|<--------------------->|
|-|-|-|-|-|-|-|-|-|-|-|-|-|-|-|-|-|-|-|-|-|-|-|-|-|-|-|-|->time
S S S S
|-| represents 1 time slot (the time it take to send 1 cell).
S represents a cell being sent.
= 16 timeslots
x 4 slots/cell
4 cells
S S S
= 12 timeslots
x 4 slots/cell
3 cells
IBM Processor for Network Resources
S ...
Transmit Buffer (CSKED)
Page 277 of 676
IBM3206K0424