RFC 895 (rfc895) - Page 2 of 3

Standard for the transmission of IP datagrams over experimental Ethernet networks

RFC 895                                                       April 1984


Address Mappings

   The mapping between 32-bit Internet addresses to 8-bit Experimental
   Ethernet addresses can be done several ways.

   The easiest thing to do is to use the last eight bits of host number
   part of the Internet address as the host's address on the
   Experimental Ethernet.  This is the recommended approach.

   Broadcast Address

      The broadcast Internet address (the address on that network with a
      host part of all binary ones) should be mapped to the broadcast
      Experimental Ethernet address (address zero).

Trailer Formats

   Some versions of Unix 4.2bsd use a different encapsulation method in
   order to get better network performance with the VAX virtual memory
   architecture.  Consenting systems on the same Ethernet may use this
   format between themselves.

   No host is required to implement it, and no datagrams in this format
   should be sent to any host unless the sender has positive knowledge
   that the recipient will be able to interpret them.  Details of the
   trailer encapsulation may be found in [6].

   (Note:  At the present time Unix 4.2bsd will either always use
   trailers or never use them (per interface), depending on a boot-time
   option.  This is expected to be changed in the future.  Unix 4.2bsd
   also uses a non-standard Internet broadcast address with a host part
   of all zeroes, this will also be changed in the future.)

Byte Order

   As described in Appendix B of the Internet Protocol
   specification [1], the IP datagram is transmitted over the Ethernet
   as a series of 8-bit bytes.












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