ethernet.h revision 17455 
1/*
2 * Fundamental constants relating to ethernet.
3 *
4 * $Id: ethernet.h,v 1.1 1996/08/05 14:02:38 phk Exp $
5 *
6 */
7
8#ifndef _NET_ETHERNET_H_
9#define _NET_ETHERNET_H_
10
11/*
12 * The number of bytes in an ethernet (MAC) address.
13 */
14#define	ETHER_ADDR_LEN		6
15
16/*
17 * The number of bytes in the type field.
18 */
19#define	ETHER_TYPE_LEN		2
20
21/*
22 * The number of bytes in the trailing CRC field.
23 */
24#define	ETHER_CRC_LEN		4
25
26/*
27 * The length of the combined header.
28 */
29#define	ETHER_HDR_LEN		(ETHER_ADDR_LEN*2+ETHER_TYPE_LEN)
30
31/*
32 * The minimum packet length.
33 */
34#define	ETHER_MIN_LEN		64
35
36/*
37 * The maximum packet length.
38 */
39#define	ETHER_MAX_LEN		1518
40
41/*
42 * A macro to validate a length with
43 */
44#define	ETHER_IS_VALID_LEN(foo)	\
45	((foo) >= ETHER_MIN_LEN && (foo) <= ETHER_MAX_LEN)
46
47/*
48 * Structure of a 10Mb/s Ethernet header.
49 */
50struct	ether_header {
51	u_char	ether_dhost[ETHER_ADDR_LEN];
52	u_char	ether_shost[ETHER_ADDR_LEN];
53	u_short	ether_type;
54};
55
56/*
57 * Structure of a 48-bit Ethernet address.
58 */
59struct	ether_addr {
60	u_char octet[ETHER_ADDR_LEN];
61};
62
63#endif
64