User guide

Summary for older GMACII revisions

 ARP request filter:

Only valid ARP-requests are accepted (length and type)

 ICMP request filter:

Only valid ICMP-requests (ping request) are accepted (length and type, echo request)

 IP filter:

Only UDP/IP frames and TCP/IP frames are accepted, other types are discarded (length and

type)

 LEN filter:

To minimize the test-overhead for the cpu, the length of ARP-requests (fix), ICMP-requests

and IP-frames is validated, this can not be switched off.

Frames can not use options in the protocols or other header types.

Example: an incorrect IP-frame tells a length of 100 byte but the real received frame has 1300

bytes, this frame is discarded by this filter.

 CRC filter:

The crc filter is always running and accepts frames only, when the correct crc is found in the

last 4 bytes of a frame. This filter can not be switched off.