Ethernet Chip Suggestion

As in, a runt frame that is 2 bytes long? Or, did you mean something else?

The controllers I've looked at support turning off the MAC-layer error-checking, so you should be able to receive clobbered packets in the buffer. How short, I can't say, as this is a really niche need.

I'd say, you'll need to read some datasheets, find some that look promising, and test them. Sounds like a lot of time & effort.

If it's not worth that much trouble, talk to Network General (Sniffer manufacturer) and see what they have to say about your needs. They're most likely to know of a device / card / setup that could do this, but it'll likely cost a lot.

Richard

It would cost too much time, so i came here to find someone have ever done this before. BTW: Most of datasheets do not provide the minimum frame length limited.

I know the ASIX AX88796L has a setting that allows you to read from the FIFO queue (4 bytes long, I think) that's in front of the packet buffer. And, it offers an option to disable CRC checking and IIRC accept errored packets. Access to the FIFO queue would seem to be as close to the wire as you can get with a normal Ethernet controller, so perhaps it's capable. (You can get test boards at

It's a rare niche of folks who would test for this knowledge - primarily packet capture / protocol analysis creators. Patrick seems to be one such person. Others may be found on the Sourceforge Ethereal project, at Network General, or at Wild Packets.

May I ask, what is your project that you need to salvage such small bits of damaged packets?

Have you considered FPGA or DSP decoding of the front-end signal, as someone else has suggested?

Regards, Richard

I am doing some research on network collisions that would need a small runt capture. I think it is the best way to achieve the goal with mature chips. FPGA and DSP may cost too much time. at the same time, AX88796L's datasheet does not show the limit, that plus much risk on our work:(. Thank you!

Most Ethernet controller can receive small packets. But you may have to write our own mac lever driver for the chip can configure it to do that. The small frames may come back with error bits set in the status, which are ignored since you wrote the driver.

Btw, I was a past Network General driver engineer, but that was many years ago and the company has been sold/merged with MacAfee in 1998 and that spun off again recently in 2004

Good luck, not for the faint at heart for those who haven't ever wrote hardware drivers before.

cel

else?