**      $Filename: ethernet.txt $
**      $Revision: 1.2 $
**      $Date: 92/01/10 15:18:46 $


#define S2WireType_Ethernet             1

ios2_DataLength:
        valid ethernet packets have 64 to 1500 bytes of data.

Address format:
        Ethernet addresses consist of 47 bits of address information and
        a 1 bit multicast flag. The standard for expressing ethernet
        addresses is as 6 bytes (octets) in the order in which the bytes
        are transmitted with the low-order bits in a byte transmitted
        first. The multicast flag bit is the least-significant bit of the
        first byte.

        Ethernet addresses in a Sana2IOReq occupy the first 6 bytes of
        an address field in transmission order with the low-order bits in
        a byte transmitted first.

Station Address:
        Each ethernet board must have a unique ethernet hardware address.
        Drivers will override any attempt to set the address to anything
        other than the ROM address.

Raw reads and writes:
        6 bytes of destination address,
        6 bytes of source address,
        2 bytes of type,
        64 to 1500 bytes of data
        (followed by 4 byte CRC value covering all of the above
         which is hardware generated and checked, hence not included
         in even raw packets)

Multicast:      Supported

Broadcast:      Supported

Promiscuous:    Supported

Packet Type Numbers for Ethernet are assigned by:

        Xerox Corporation
        Xerox Systems Institute
        475 Oakmead Parkway, Sunnyvale, CA 94086
        Attn: Ms. Fonda Pallone
        (408) 737-4652


Some Common Packet Type Numbers:

      decimal  Hex        Description
      -------  ---        -----------
         000   0000-05DC  IEEE 802.3 Length Field
        2048   0800       TCP/IP -- IP
        2054   0806       TCP/IP -- ARP
       32821   8035       TCP/IP -- RARP
       32923   809B       Appletalk
       33011   80F3       AppleTalk AARP (Kinetics)
       33100   814C       SNMP
       33079   8137-8138  Novell, Inc.