dm9302 Davicom Semiconductor, Inc., dm9302 Datasheet - Page 50

• Manufacturer Part Number: dm9302
• Description: 10/100mbps Ethernet Fiber/twisted Pair Media Converter With Local Bus
• Manufacturer: Davicom Semiconductor, Inc.

packet is seen on the wire. The detail description of
partition mode represent following:
the following conditions occurs:
consecutive re-transmit attempts to the same packet.
for more than 512 bit times.
the transmitting packet is deferred to long.
packet, regardless of the collision detection, and will
not allow the usual Back-off Algorithm. Additional
packets pending for transmission will be transmitted,
while ignoring the internal collision indication. This
frees up the ports transmit buffers which would
otherwise be filled up at the expense of other ports
buffers.
signifying
connection/cable/station), thus dropping packets is a
small price to pay vs. the cost of halting the switch
due to a buffer full condition.
end of a successful packet transmission.
successful packet transmission is defined as no
collisions were detected on the first 512 bits of the
transmission.
broadcast or multicast packets, to protect the switch
from lower bandwidth availability.
one is throttling broadcast packet only, the other
includes multicast. This feature can be set through bit
1 of register 61h.
programmed by EEPROM or register 67h, the default
setting is no broadcast storm protecting.
control for each port. One is the ingress and egress
bandwidth rate can be control separately, the other is
combined together, this function can be set through
50
9.2.10 Broadcast Storm Filtering
9.2.11 Bandwidth Control
(1). Entering Partition State
A port will enter the Partition State when either of
(2). While in Partition state:
The port will continue to transmit its pending
(3). Exiting from Partition State
The Port exits from Partition State, following the
The DM9302 has an option to limit the traffic of
There are two type of broadcast storm control,
The
The DM9302 supports two type of bandwidth
The port detects a collision on every one of 64
The port detects a single collision which occurs
Transmit defer timer time out, which indicates
broadcast
The assumption is that the partition is
a
system
storm
failure
threshold
10/100Mbps Ethernet Fiber/Twisted Pair Media Converter with Local bus
situation
can
(bad
be
A
bit 3 of register 61h. The bandwidth control is
disabled by default.
threshold rate is defined in register 66h. For
combined mode, it is defined in register 67h.
is enabled, Pause or Jam packet will be transmitted.
The ingress packets will be dropped if flow control is
disabled.
transmit any packets. On the other hand, the ingress
bandwidth of source port will be throttled that prevent
packets from forwarding.
egress bandwidth over threshold, the bandwidth will
be throttled.
on per port base, detail as below:
port” by register 52h, multiple ports can be set as
“receive monitor port” or “transmit monitor port” in
per-port register 65h.
are send a copy to “sniffer port”. For example, port 0
is set as “receive monitor port” and port 3 (processor
port) is selected as “sniffer port”. If a packet is
received form port 0 and destined to port 1 after
forwarding decision, the DM9302 will forward it to port
1 and processor port in the end.
port” are send a copy to “sniffer port”. For example,
port 1 is set as “transmit monitor port” and processor
port is selected as “sniffer port”. If a packet is
received from port 0 and predestined to port 1 after
forwarding decision, the DM9302 will forward it to port
1 and processor port in the end.
broadcast/multicast packets are not monitored (see
bit 4 of register 65h). It’s useful to avoid unnecessary
bandwidth.
9.2.12 Port Monitoring Support
For separated bandwidth control mode, the
The behavior of bandwidth control as below:
(1).For the ingress control, if flow control function
(2).For the egress control, the egress port will not
(3).In combined mode, if the sum of ingress and
The DM9302 supports “Port Monitoring” function
(1). Sniffer Port and Monitor Port
There is only one port can be selected as “sniffer
(2).Receive monitor
All packets received on the “receive monitor port”
(3).Transmit monitor
All packets transmitted on the “transmit monitor
(4).Exception
The DM9302 has an optional setting that
DM9302
Preliminary datasheet
DM9302-15-DS-P01
July 30, 2009