Hi,
I am using the MPC8260 FCC2 for ethernet communication.
Its configured for 10 Mbps and Half Duplex.
I am facing a problem which writes the header twice in
the buffer pointed to by the buffer pointer.
The buffer descriptor is fine and even the allocation
of bytes for the buffer is OK.

But the header is written twice and bcoz of this
the buffer end mark gets over written.

Problem:
The ethernet driver has 16 buffers allocated and data is written to the
allocated buffer with the size 0x611 = 1553 = alloc (1520 + 33 bytes)
Ethernet
+---------+---------+---------+---------- | Dst | Src | Type | Data...
+---------+---------+---------+---------- <-- 6 --> <-- 6 --> <-- 2 -->
<-46-1500->
The buffer sizes and the administration data are ok.
The problem is that the ethernetheader is written 2 times as shown ,
which causes the BUFFER ENDMARK to be overwritten.

Start of the BUFFER:
00 80 37 A9 58 93 00 03 BA 68 40 E1 08 00 45 00 05 DC 01 AB 40 55 55
55 55 55 55 55 55 55 55 55 contd...
|---- Dst --------------- |----- Src ----------------| type
|.......Data............
contd.. 00 80 37 A9 58 93 00 03 BA 68 40 E1 08 00 45 00 05 DC 01 AB 40
00 40 06 E6 F7 0A 45 1B F6 0A 45 1B FA 8A 32 C1 0D E6 BE D0 4C 8A ...
|---- Dt ---------------- |----- Src------------ ----| type |
.......Data.........

The HEADER which includes the Destination and Source Address along with
the frame type should only be written once.


BUFFER END MARK refers to the end of the buffer actually allocated for
a
particular ethernet frame.


If any one has faced similar problem kindly respond.

Thanks & Regards,

Eshwar
Engineer-R&D
CMC Limited
India
email: esh8260@yahoo.com