
IP113
IEEE 802.3x
Preliminary, Specification subject to change without notice
IP113-DS-P07
Jul. 19, 2002
12
The IEEE 802.3x is used for flow control in full duplex
mode if both IP113 (X_en=1) and the remote station
have IEEE802.3x capability. When the level of occupied
buffer of a port is over set threshold, it will send a
PAUSE frame with maximum delay FFFF. The remote
station will stop to transmit the next packet after
receiving the PAUSE frame. After level of the occupied
buffer is below release threshold, the port sends out a
PAUSE frame with zero delay to resume receiving the
incoming packets. The remote station is re-enable to
transmit packets after receiving the PAUSE frame with
zero delay. While level of the occupied buffer of a port is
over set threshold, IP113 re-transmits the PAUSE frame
with maximum delay to ensure the pause timer of the
remote station does not expire and begins transmission.
The IPG between PAUSE frames is 42ms(100M) or
420ms(10M).
When an incoming PAUSE frame with non-zero delay is
received, the port stops the next frame transmission and
starts its pause timer. It is re-enabled transmission
function either the pause timer is expired or a PAUSE
frame with zero delay is received. If another pause frame
is received before the timer expires, the timer will be
updated with the new value. During this period, only
PAUSE frame from IP113 will be transmitted.
PAUSE Frame Format
Destination
01-80-C2-00-00-01
6 bytes
Source
SA
6 bytes
Type
8808
2 bytes
Opcode
0001
2bytes
Pause Timer
FFFF(0000)
2 bytes
Pad
CRC
CRC
4 bytes
PAD with zero
42 bytes