pxf4336 Infineon Technologies Corporation, pxf4336 Datasheet - Page 106

• Manufacturer Part Number: pxf4336
• Description: Abm Premium Atm Buf Fer Manager
• Manufacturer: Infineon Technologies Corporation

3.5.1.5
The EFCI bit is carried in user data cells and supposed to be set in congested nodes. At
the ABR destination the EFCI state is maintained in a status bit.
When the EFCI status bit is set and the destination turns around an RM cell, it sets CI=1
before sending the BRM and resets its EFCI status bit.
EFCI marking is a cheap way to enable ABR, because the node doesn’t need to update
BRM cells, however the control response is slow.
The ABM-P supports EFCI marking by setting the EFCI bit in outgoing data cells. The
value of the EFCI bit is calculated by the Cell Acceptance Algorithm (see
Section
Outgoing EFCI = 1 if and only if incoming EFCI = 1 or threshold QueueCiCLP1 has been
exceeded and either the last arrived cell has been discarded or one of the buffer
management thresholds BufCiCLP1 or SBCiCLP1 has also been exceeded.
Since the ABM-P chip provides more advanced mechanisms, it is not recommended to
rely solely on EFCI marking for ABR.
3.5.1.6
The Relative Rate Marking mechanism uses two bits in the RM cell to convey information
about congested nodes: Congestion Indication (CI) and No Increase (NI).
The ABM-P supports Relative Rate Marking by calculating local values of CI and NI in
the Cell Acceptance Algorithm (see
as follows:
Outgoing CI = 1 if and only if incoming CI = 1 or threshold QueueCiCLP1 has been
exceeded and either the last arrived cell has been discarded or one of the buffer
management thresholds BufCiCLP1 or SBCiCLP1 has also been exceeded.
Outgoing NI = 1 if and only if incoming NI = 1 or threshold QueueCiCLP1 has been
exceeded or either the last arrived cell has been discarded or one of the buffer
management thresholds BufCiCLP1 or SBCiCLP1 has been exceeded.
3.5.1.7
The Explicit Rate Marking mechanism uses the Explicit Rate (ER) field in the RM cells
to convey an estimate for the appropriate source rate. By default, the BRM cells are
used. Updating of FRM cells instead is optional.
The ABM-P supports Explicit Rate Marking by calculating a local ER in the ERC unit (see
Section
the current logical queue length of the ABR connection and updating the outgoing ER
field of BRM cells as: outgoing ER = min(incoming ER, local ER). The updating is only
enabled when the TCT parameter ABRen is set to 1.
Data Sheet
3.4.1.7) as follows:
3.5.2) depending on a measurement of the current emitted cell rate (CCR) and
EFCI Marking
Relative Rate Marking
Explicit Rate Marking
Section
106
3.4.1.7) and setting the outgoing CI and NI
Functional Description
PXF 4336 V1.1
2001-12-17
ABM-P