L-ET4148-50C-DB LSI, L-ET4148-50C-DB Datasheet - Page 37

• Manufacturer Part Number: L-ET4148-50C-DB
• Manufacturer: LSI

Specifications of L-ET4148-50C-DB

• Lead Free Status / RoHS Status: Supplier Unconfirmed

Preliminary Data Sheet
April 2006
Agere Systems Inc.
Functional Description
Packet Transmission
The packet transmission process merges the regular network transmit packets with the full-duplex flow control
packets and delivers the packets to the attached network.
Full-duplex flow control packets are given equal priority to normal transmit packets and are simply merged into the
transmit flow on a round-robin basis. Flow control packets are only sent when the packet buffer is congested, and
even then, they are not sent very often relative to the rate that normal packets may be transmitted.
If a packet was modified during its traversal of the ET4148-50, a new CRC value is computed by the transmitting
Ethernet MAC. Otherwise, the CRC received with the packet is used for transmission.
Single-Chip 48 x 1 Gbit/s + 2 x 10 Gbits/s Layer 2+ Ethernet Switch
(continued)
Figure 15. Packet Transmission Processes
Y
Agere Systems - Proprietary
TRANSMIT PACKET
CURRENTLY
TRANSMIT
MODIFIED?
PENDING?
PAUSING?
START
PACKET
PACKET
DONE
N
Y
N
CONTROL PACKET
N
Y
TRANSMIT FLOW
CONTROL
PENDING?
PACKET
FLOW
COMPUTE NEW CRC
Y
N
ET4148-50
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