>Could someone please post (a link to an) explanation of how mbufs work,
>because I'm completely mystified by what the other drivers are doing
>here.

	I would recommend the following book.

itojun


TCP/IP Illustrated, Vol. 2 (top)

Authors: Gary R. Wright, W. Richard Stevens
Publication: Addison Wesley, 1995 (ISBN 0-201-63354-X)