AC208-DS03-R datasheet(14/58 Pages) BOARDCOM

14 / 58 page

AC208

Preliminary Data Sheet

07/08/02

B roa dcom

Page 6

Bridge Function

Document

AC208-DS04-405-R

BRIDGE FUNCTION

MEDIA INDEPENDENT INTERFACE

The bridge supports MII for 10/100 Mbps. Port 0 of bridge can support either 10 or 100, while port 1 supports only at

100 Mbps. Refer to the mode pin table to configure port 0.

FORWARDING SCHEME

The bridge supports the store-and-forward scheme only. It does not support cut-through-mode. With store-and-forward, the

incoming packet should be completely received to the buffer without error before it can be sent out.

ADDRESS RECOGNITION

The self-learning bridge function is based on source address field of packets. The bridge uses the XOR hashing algorithm

to address look-up table. Programmable aging time and fast aging control is supported.

RESET AND RESTART

At power on, the bridge initially goes to the SRAM self-test mode. It generates eight patterns to evaluate SRAM status.

MEDIA ACCESS CONTROL

The bridge media access control (MAC) complies with certain IEEE 802.3 MAC protocols such as frame formatting and

collision handling, but does not generate CRC codes. It generates a 56-bit preamble and start of frame delimiter while a

packet is sending. In half-duplex mode, the device listens before transmitting, to prevent traffic jam. During collision, a packet

is retransmitted at a random time.

AC208-DS03-R 数据表(PDF) 14 Page - Broadcom Corporation.