Ndis Packet Size

I have IM-driver based on passthru sample.
It works with standard ethernet adapter.
Sometimes I observe strange OUTGOING packets with large size.
Too large for ethernet !!! Sometimes it’s size reaches 4 Kilobytes
As far as I understand these packets contain SMB-packets.

How can this be ?
Frankly speaking, I dont like them. Is there any way to make these
packets be normal size ?

Athlon - 1400Mhz
Memory - 256Mb
Network Adapter - Intel pro 100s

Best regards,
foxgen mailto:xxxxx@yandex.ru