2

AT79C1030

3435BS–NETST–6/04

also supports filtering special packets to prevent unnecessary flow, such as broadcast storms,

so broadcast/ARP packets can be discarded according to user settings.

Overview

Ethernet Packet

Reception and

Transmission

The AT79C1030 complies with the IEEE 802.3 MII/GMII specification. The switch supports

full/half duplex mode.

•

In full-duplex mode, from the same port, the switch receives and transmits packets at the

same time; line flow control is performed by sending or resolving pause frames.

•

In half-duplex mode, reception and transmission can't take place from the same port at the

same time. When a collision occurs, the packet should be retransmitted according to the

back-off algorithm. Line flow control is implemented by the back-pressure algorithm.

The switch works in 10/100/1000Mb/s in both full/half duplex modes. The full or half duplex

mode and data rate are selected via auto-negotiation or manually. In order to support auto-

negotiation the MDIO interface is implemented.

Receiving Operation

The device calculates the size of an ingress packet and decides whether the size of the packet

is legal. At the same time, a CRC check is performed to verify whether the input packet data is

right.

Transmitting Operation

The switch adds, removes, or changes the tag of the egress packet according to the related

settings. The device re-calculates the CRC of this packet again to ensure sending the right

packet in case the packet data is modified.

Figure 1. AT79C1030 Block Diagram

MAC

DMA

FIFO

POR

T7

TX

RX

RX

MEMORY

MANAGER

MEMORY

SWITCH

CORE

RS-232

CPU

REGISTER

VLAN

TABLE

MAC

TABLE

SMI

MDC

MDIO

MAC

DMA

FIFO

POR

T0

TX

MAC

DMA

FIFO

POR

T1

TX

RX

MAC

DMA

FIFO

POR

T6

TX

RX

8 GMII/MII