Network Working Group V. Cerf
Request for Comments: 696
Comments on IMP/HOST and HOST/IMP Protocol Changes
With reference to RFC's 687, 690
, and 692 (NIC's 32564, 32699
32734, respectively) by D.C. Walden, J. Postel, and S. Wolfe
(respectively), I would like to offer some observations relative to
current international standards recommendations from working group
6.1 of the International Federation of Information Processing. In a
meeting held last May at the NCC, this working group voted to present
a recommendation to CCITT (International Consultative Committee on
Telephony and Telegraphy of the International Telegraphics Union) for
a standard packet (or DATAGRAM) header.
The proposed packet header format is meant to interface hosts to
packet networks. It is not a header for Host-to-Host protocol, nor
is it an IMP-to-IMP header. The bulk of the header is taken up with
addressing space(96 bits!) since this will be compatible with the
current maximum address space of the telephone system (14 digits).
LOCAL NETWORK FIELD - 4 bits
This field allows local networks to operate easily on multiple
formats, since the 4 bits can be used in any fashion desired by
the local network.
DATAGRAM FORMAT - 4 bits
This field could be used by ARPANET to contain "1001" binary, so
as to maintain backward compatibility with the existing message
PACKET TYPE CODE - 8 bits
This could be used for the HOST/IMP and IMP/HOST code.
FACILITIES - 16 bits
These bits have not yet been specifically allocated. Some will no
doubt be for international services (e.g., tracing at gateways
between networks, accounting, class of service). It was the
feeling of WG 6.1 members that some of these bits (e.g., 8
be allocated to the originating network (or destination network)
for its own use.