Ethernet
Hello,
I am working on Embedded Ethernet, without using a MAC controller on my Board. I have created ethernet packets and am transmitting it from the board. The packets are not received on PC and Protocol analyzer indicates CRC error. But I am sure that the CRC calculated on the board is correct as I have verified it for packets that have been received from PC and calculated the same on my board.
Can you suggest me something that can be used for finding out the exact error, or receiving the corrupted packets on PC?
Regards,
Naeem
Software/Hardware used:
Software/Hardware used:
ASKED:
May 5, 2005 2:18 AM
UPDATED:
May 8, 2005 10:17 PM
Answer Wiki:
Gee - such an open ended question. A - which version of IEEE 802 are you trying to implement? B - What format of media are you using, Coax, UTP, proprietary? C - If we cut to the chase and presume 802.3 and TCP/IP and UTP (RJ45) connetions and 10MB half or full, then you need a crossover cable from device to PC. [No MAC then you cannot use a hub or switch!] At that point 'Google' Ethereal and WinCap to setup a workstation that can capture packets and display them on the PC [if using Linux instead of Windows you won't need WinCap].
Without a MAC address then DHCP and DNS won't work and forget going through switches or routers.
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The NAC address IS the layer one. Without it, there is no way to find it on a network.
The MAC address IS the layer one. Without it, there is no way to find it on a network.
Ok, let’s look at this a little differently.
As Howard2nd pointed out, you’ve not specified which of several “ethernet” specifications you’ve based your efforts on. 802.3, 10BaseT or what?
Assuming 802.3…
1) Do you have the preamble in place? (7 bytes of 10101010)
2) Are you using basic or differential Manchester encoding?
3) Do you have the “Start of Frame” byte in place?
4) Are your frames at least 64 bytes long?
5) If not, have you padded them out to that minimum length?
6) What is the range of the packet being used to calculate the checksum?
7) Have you used an oscilloscope to verify presence or absence of electrical noise on the wire which could render the checksum invalid due to corruption of data bits?
Bob