[src/trunk]: src/sys/net Define several constants related to the Ethernet pro...

[thorpej <thorpej%NetBSD.org@localhost>]

details:   https://anonhg.NetBSD.org/src/rev/eb855ed3a867
branches:  trunk
changeset: 467556:eb855ed3a867
user:      thorpej <thorpej%NetBSD.org@localhost>
date:      Thu Mar 25 23:08:28 1999 +0000

description:
Define several constants related to the Ethernet protocol:
- ETHER_ADDR_LEN: length of Ethernet address (actually, we already defined
  this).
- ETHER_TYPE_LEN: length of the Ethernet header `type' field.
- ETHER_CRC_LEN: length of the Ethernet CRC (explorer got this already, mostly
because I forgot to commit these changes earlier).
- ETHER_HDR_LEN: total length of the Ethernet header
- ETHER_MAX_LEN: maximum length of an Ethernet frame, including header and CRC
- ETHER_MIN_LEN: minimum length of an Ethernet frame, including header and CRC

Define ETHERMTU and ETHERMIN (payload sizes) in terms of the above constants.

diffstat:

 sys/net/if_ether.h |  21 ++++++++++++++-------
 1 files changed, 14 insertions(+), 7 deletions(-)

diffs (51 lines):

diff -r 1d4e0dadb6be -r eb855ed3a867 sys/net/if_ether.h
--- a/sys/net/if_ether.h        Thu Mar 25 22:38:28 1999 +0000
+++ b/sys/net/if_ether.h        Thu Mar 25 23:08:28 1999 +0000
@@ -1,4 +1,4 @@
-/*     $NetBSD: if_ether.h,v 1.6 1999/03/25 04:45:37 explorer Exp $    */
+/*     $NetBSD: if_ether.h,v 1.7 1999/03/25 23:08:28 thorpej Exp $     */
 
 /*
  * Copyright (c) 1982, 1986, 1993
@@ -39,18 +39,26 @@
 #define _NET_IF_ETHER_H_
 
 /*
+ * Some basic Ethernet constants.
+ */
+#define        ETHER_ADDR_LEN  6       /* length of an Ethernet address */
+#define        ETHER_TYPE_LEN  2       /* length of the Ethernet type field */
+#define        ETHER_CRC_LEN   4       /* length of the Ethernet CRC */
+#define        ETHER_HDR_LEN   ((ETHER_ADDR_LEN * 2) + ETHER_TYPE_LEN)
+#define        ETHER_MIN_LEN   64      /* minimum frame length, including CRC */
+#define        ETHER_MAX_LEN   1518    /* maximum frame length, including CRC */
+
+/*
  * Ethernet address - 6 octets
  * this is only used by the ethers(3) functions.
  */
 struct ether_addr {
-       u_int8_t ether_addr_octet[6];
+       u_int8_t ether_addr_octet[ETHER_ADDR_LEN];
 };
 
 /*
  * Structure of a 10Mb/s Ethernet header.
  */
-#define        ETHER_ADDR_LEN  6
-
 struct ether_header {
        u_int8_t  ether_dhost[ETHER_ADDR_LEN];
        u_int8_t  ether_shost[ETHER_ADDR_LEN];
@@ -61,9 +69,8 @@
 
 #define        ETHER_IS_MULTICAST(addr) (*(addr) & 0x01) /* is address mcast/bcast? */
 
-#define        ETHERMTU        1500
-#define        ETHERMIN        (60-14)
-#define        ETHER_CRC_LEN   4
+#define        ETHERMTU        (ETHER_MAX_LEN - ETHER_HDR_LEN - ETHER_CRC_LEN)
+#define        ETHERMIN        (ETHER_MIN_LEN - ETHER_HDR_LEN - ETHER_CRC_LEN)
 
 #ifdef _KERNEL
 /*