RTL8306SD/RTL8306SDM
Datasheet
7.1.5.
Half Duplex Operation
In half duplex mode, the CSMA/CD media access method is the means by which two or more stations
share a common transmission medium. To transmit, a station waits (defers) for a quiet period on the
medium (that is, no other station is transmitting) and then sends the intended message in bit-serial form. If
the message collides with that of another station, then each transmitting station intentionally transmits for
an additional predefined period to ensure propagation of the collision throughout the system. The station
remains silent for a random amount of time (backoff) before attempting to transmit again.
When a transmission attempt has terminated due to a collision, it is retried until it is successful. A
controlled randomization process called ‘truncated binary exponential backoff’ determines the scheduling
of the retransmissions. At the end of enforcing a collision (jamming), the switch delays before attempting
to retransmit the frame. The delay is an integer multiple of slotTime (512 bit times). The number of slot
times to delay before the nth retransmission attempt is chosen as a uniformly distributed random integer
‘r’ in the range:
0 ≤ r < 2k
where:
k = min (n, backoffLimit). IEEE 802.3 defines the backoffLimit as 10.
7.1.6.
InterFrame Gap
The InterFrame Gap is 9.6µs for 10Mbps Ethernet and 960ns for 100Mbps Fast Ethernet.
7.1.7.
Illegal Frame
Illegal frames such as CRC error packets, runt packets (length < 64 bytes), and oversize packets (length >
maximum length), will be discarded.
6-Port 10/100Mbps Single-Chip Dual MII/RMII Switch Controller
38
Track ID: JATR-1076-21 Rev. 1.1
REALTEK [ Realtek Semiconductor Corp. ]
