ZL50418GKC ZARLINK [Zarlink Semiconductor Inc], ZL50418GKC Datasheet - Page 38

• Manufacturer Part Number: ZL50418GKC
• Description: Managed 16-Port 10/100 M + 2-Port 1 G Ethernet Switch
• Manufacturer: ZARLINK [Zarlink Semiconductor Inc]

The following registers define the size of each section of the Frame data Buffer:
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7.9.1
Summarizing the two examples of local dropping discussed earlier in this chapter:
If a queue is a delay-bounded queue, we have a multilevel WRED drop scheme designed to control delay and
partition bandwidth in case of congestion.
If a queue is a WFQ-scheduled queue, we have a multilevel WRED drop scheme designed to prevent congestion.
In addition to these reasons for dropping, we also drop frames when global buffer space becomes scarce. The
function of buffer management is to make sure that such dropping causes as little blocking as possible.
7.10
Because frame loss is unacceptable for some applications, the ZL50418 provides a flow control option. When flow
control is enabled, scarcity of buffer space in the switch may trigger a flow control signal; this signal tells a source
port that is sending a packet to this switch to temporarily hold off.
PR100- Port Reservation for 10/100 Ports
PRG- Port Reservation for Giga Ports
SFCB- Share FCB Size
C2RS- Class 2 Reserve Size
C3RS- Class 3 Reserve Size
C4RS- Class 4 Reserve Size
C5RS- Class 5 Reserve Size
C6RS- Class 6 Reserve Size
C7RS- Class 7 Reserve Size
ZL50418 Flow Control Basics
Dropping When Buffers Are Scarce
reservation
reservation
temporary
per-class
Figure 13 - Buffer Partition Scheme Used to Implement Buffer Management
(24 10/100 M, CPU)
reservations
per-source
Zarlink Semiconductor Inc.
ZL50418
38
shared pool S
Data Sheet