IP178C-DS-R09 datasheet(32/93 Pages) ETC2

32 / 93 page

IP178C/IP178C LF/IP178CH/IP178CH LF

Datasheet

32/93

June 21, 2007

IP178Cx-DS-R12

2.1

Flow control

IP178C/IP178CH jams or pauses a port, which causes output queue over the threshold. Its link partner

will defer transmission after detecting the jam or pause frame. A port of IP178C/IP178CH defers

transmission when it receives a jam or a pause frame.

IP178C/IP178CH issues pause control frame (Pause On, time slot count = 0xffff) to remote station when the

output queue of the destination port is higher than high water mark threshold. When the output queue of

the destination port is lower than low water mark threshold, IP178C/IP178CH issues pause control frame

(Pause Off, time slot count = 0) to restart transmition. Besides, IP178C/IP178CH provides an additional

protect function, when it issues continuous 16 times of Pause ON frame (network abnormal), no more Pause

ON frame will be send.

When CoS is enabled, IP178C/IP178CH may disable the flow control function for a short term to

guarantee the bandwidth of high priority packets. A port disables its flow control function for 2 ~ 3

seconds when it receives a high priority packet. It doesn’t transmit pause frame or jam pattern during the

period but it still responses to pause frame or jam pattern.

The flow control function can be enabled by pulling up pin 75 X_EN or by programming MII register

30.1.10.

IP178C-DS-R09 数据表(PDF) 32 Page - List of Unclassifed Manufacturers