MDS213 Datasheet, PDF (48/120 Pages) Zarlink Semiconductor Inc – 12-Port 10/100Mbps + 1Gbps Ethernet Switch

MDS213
Master dev sub-frame
16 slots
One Frame
256x80nsec
Slave dev sub-frame
16 slots
Data Sheet
Cycle #0 Cycle #1 Cycle #2 Cycle #3 Cycle #4 Cycle #5 Cycle #6 Cycle #7 Cycle #8
LED_CLKO
LED_SYNCI/O
LED_DI/O
P0
bit 0
bit 1
bit 2
bit 3
bit 4
bit 5
bit 6
bit 7
1* one pulse for every 256 cycles
P1
bit 0 bit 1
Figure 18 - Time Diagram of LED Interface
12.0 Data Forwarding Protocol and Data Flow
12.1 Data Forwarding Protocol
12.1.1 Frame Reception
For normal frame reception, a 128-byte block of frame data is stored in the RxFIFO. This block may be shorter if an
End of Frame (EOF) arrives. At that point, the RxDMA will request the use of the internal memory bus. When this
memory request is granted, the RxDMA will move the block from the RxFIFO to the Frame Data Buffer (FDB).
The MAC ports are partitioned into two groups, one for the Gbps Port and one for all 12 of the 100Mbps Ports. The
service discipline is round robin for both the Gbps Port and 100/10Mbps group. After the entire frame is moved to
the frame data buffer (FDB), a switch request will be sent to the Search Engine (Reference Search Engine Section)
12.1.2 Unicast Frame Forwarding
For forwarding of the unicast frame, the Search Engine first resolves the destination device and the destination
port, and sends a switch response is sent back to the Frame Engine. The Frame Engine will obtain the type (unicast
or multicast), the destination port, and the destination device from the search response. After processing the search
response, the Frame Engine will notify the destination port that it has a frame to forward to the destination port's
TxFIFO.
For local forwarding (e.g. the destination port is in the local device), the Frame Engine will send the job to the
Transmission Scheduling queue of the destination port.
For remote forwarding (i.e. the destination port is in the remote device), the Frame Engine will create a data
forwarding request command message (DATA_FWD_REQ), which is sent via the XPipe to the remote device. The
remote Frame Engine, after receiving this DATA_FWD_REQ message, will place a job in the Transmission
Scheduling queue of the destination port.The port will serve the next job from the Transmission Scheduling queue
when the following two conditions are met:
• It is enough room for a 1.5Kbyte frame (a maximum-sized frame) within the TxFIFO.
• The end-of-frame (EOF) of the current frame has arrived at the TxFIFO.
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