Network Working Group Vint Cerf
Request for Comments: 22
October 17, 1969
Host-Host Control Message Formats
has been modified at UCLA; and will be republished. In
the meantime, it seems important to report a new control message
format which does not use 7-bit ASCII character mode of transmission.
All Host-Host control messages consist of sequences of 8-bit bytes of
<control byte> <parameter byte l> ... <parameter byte n>
It is reasonable to transmit more than one control message in any
given packet, although this is not mandatory.
control messages have been defined by UCLA; these are
given in the table below along with their parameters. The
interpretation is given from the point of view of the transmitting
host. ("L" or "Li" mean Link#, and are binary values.)
Control byte Parameter Interpretation
<0> <L> Please establish primary connection;
our output link # is L
<1> <L,> <L2> Please establish auxiliary connection
parallel to our primary output link L.
The auxiliary output link is L2.
<2> <L1> <L2> DK primary. Your primary output link
to us was L; our primary output link
to you is L2.
<3> <L1> <L2> OK auxiliary. Your auxiliary output
link is Li, our auxiliary output link
<4> <L> Not OK primary. We cannot establish a
primary connection. Your primary
output link number was L.
<5> <Li> <L2> Not OK auxiliary. We cannot establish
an auxiliary connection. Your primary
output link no was L2.