DM8603 datasheet(73/107 Pages) DAVICOM

73 / 107 page

DM8603

10/100 Mbps 3-port Ethernet Switch Controller with MII / RMII Interface

Preliminary datasheet

DM8603-12-DS-P01

November 8, 2010

9.2.10 Broadcast Storm Filtering

The DM8603 has an option to limit the traffic of broadcast or multicast packets, to protect the switch from

lower bandwidth availability.

There are two types of broadcast storm control, one is throttling broadcast packet only, the other includes

multicast. This feature can be set through REG 08h/09h/0Ah.12h.

The broadcast storm threshold can be programmed by EEPROM or REG 08h/09h/0Ah.15h, the default

setting is no broadcast storm protecting.

9.2.11 Bandwidth Control

The DM8603 supports two types of bandwidth control for each port. One is the ingress and egress

bandwidth rate can be controlled separately, the other is combined together, this function can be set through

REG 08h/09h/0Ah.12h.[14]. The bandwidth control is disabled by default.

To separate and combined bandwidth control mode, the threshold rate is defined in REG

08h/09h/0Ah.15h.

The behavior of bandwidth control as below:

(1). For the ingress control, if flow control function is enabled, Pause or Jam packet will be transmitted.

The ingress packets will be dropped if flow control is disabled.

(2). For the egress control, the egress port will not transmit any packets. On the other hand, the ingress

bandwidth of source port will be throttled that prevent packets from forwarding.

(3). In combined mode, if the sum of ingress and egress bandwidth over threshold, the bandwidth will

be throttled.

9.2.12 Port Monitoring Support

The DM8603 supports “Port Monitoring” function on per port base, detail as below:

(1). Sniffer Port and Monitor Port

There is only one port can be selected as “sniffer port” by REG 10h.13h, multiple ports can be set

as “receive monitor port” or “transmit monitor port” in REG 08h/09h/0Ah.12h.

(2). Receive monitor

All packets received on the “receive monitor port” are send a copy to “sniffer port”. For example,

port 0 is set as “receive monitor port” and port 2 is selected as a “sniffer port”. If a packet is

received form port 0 and predestined to port 1 after forwarding decision, the DM8603 will forward it

to port 1 and port 2 in the end.

(3). Transmit monitor

All packets transmitted on the “transmit monitor port” are send a copy to “sniffer port”. For example,

port 1 is set as “transmit monitor port” and port 2 is selected as “sniffer port”. If a packet is received

from port 0 and predestined to port 1 after forwarding decision, the DM8603 will forward it to port 1

and port 2 in the end.

(4). Exception

The DM8603 has an optional setting that broadcast/multicast packets are not monitored (see REG

08h/09h/0Ah.12h.[11]). It’s useful to avoid unnecessary bandwidth.

DM8603 Datasheet(PDF) 73 Page - Davicom Semiconductor, Inc.

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