TXC-06885BIOG Transwitch Corporation, TXC-06885BIOG Datasheet - Page 67

• Manufacturer Part Number: TXC-06885BIOG
• Manufacturer: Transwitch Corporation

Specifications of TXC-06885BIOG

• Operating Supply Voltage (typ): 1.8/3.3V
• Operating Temperature Classification: Industrial
• Package Type: BGA
• Mounting: Surface Mount
• Lead Free Status / RoHS Status: Not Compliant

PRELIMINARY TXC-06885-MB, Ed. 6A
February 2005
6.1.4 Ingress FIFO Operations
6.1.4.1 Ingress FIFO Write:
6.1.4.2 Ingress FIFO Read:
Frames once qualified by the Receive MAC are written into the Ingress FIFO of the
appropriate channel. The Ingress FIFO for each channel is 7.75 KBytes deep in SMII mode,
62 KBytes deep in GMII mode, and 31 KBytes deep in extended SMII mode. The ingress
FIFO is an integral part of Envoy-CE4 IEEE 802.3 compliant Flow control mechanism, which
is used to backpressure the Ethernet interface. When the Ingress FIFO starts becoming full,
the flow control is activated (if enabled) and the device transmitting the Ethernet traffic is
backpressured. A complete description of the procedure is outlined in section
Duplex” on page
indication and attempts to overflow the Ingress FIFO, the Envoy-CE4 will truncate the frame
being received during the overflow condition. Frames received when the Ingress FIFO is in an
overflow condition are discarded and the number of discarded frames are counted. In Half
Duplex mode, the backpressure mechanism used is the “Raise Carrier” method, which is
described in section Ethernet
Frames are read out from the Ingress FIFO by the SPI-3 interface. Since the SPI-3 interface
aggregates the traffic from the channels, a channel selection is required. The selection of the
Ingress FIFO (or channel selection) for frame reads, is done by the SPI-3 interface. For
SPI-3, the selection is done by the scheduler in the Envoy-CE4 SPI-3 interface block. The
scheduler uses a round robin selection scheme.
• Count of Control frames received with unknown opcode (32 bit)
• Count of frames received with a valid FCS and length less than 64 bytes (32 bit)
• Count of frames received with a valid FCS and total byte count is between 1519 and
• Count of frames received with an invalid FCS and length less than 64 bytes (32 bit)
• Count of frames received with an invalid FCS and total byte count is between 64 and
• Count of frames received with an invalid FCS and total byte count is between 1519 and
• Count of frames dropped by the receive MAC due to Ingress FIFO full (32 bit)
• Count of frames dropped by the receive MAC due to Unicast and Source address
• Count of VLAN tagged frames received (32 bit)
• Six sets of counts for frame sizes that fall in a certain range. The ranges are 64 bytes, 65
• Count of frames received with the RX_ER asserted by the PHY during transmission (32
• Count of frames received with length error (32 bit)
maximum frame length (32 bit)
1518 bytes (32 bit)
maximum frame length (32 bit)
mismatch (32 bit)
to 127 bytes, 128 to 255 bytes, 256 to 511 bytes, 512 to 1023 bytes, and 1024 to 1518
bytes.
bit)
76. If the Ethernet device transmitting frames, ignores the backpressure
- Operation -
“Half-Duplex Flow Control” on page
76.
Envoy-CE4 Device
DATA SHEET
“Ethernet Full
TXC-06885
67 o f 12 8