RFC 781 Zaw-Sing Su SRI May 1981 A SPECIFICATION OF THE INTERNET PROTOCOL (IP) TIMESTAMP OPTION I. INTRODUCTION
An effective way to measure catenet delays is by means of packet header
Measurement of one-way delay, either end-to-end or across an individual
As an IP option, the contents of the first two octets are dictated by the
0 7 15 23 31 +---------------+---------------+---------------+---------------+ | type | length | offset |overflw| flags | +---------------+---------------+---------------+---------------+ | internet ID | +---------------+---------------+---------------+---------------+ | time stamp | +---------------+---------------+---------------+---------------+ . . .
offset = the number of octets from the beginning of this option to the end of timestamps (i.e., the beginning of space for next timestamp). It is set to one, an odd number, when no more space remains in the header for timestamps;
overflow = the number of IP modules that cannot register timestamps due to lack of space;
flag = 0 -- time stamps only
1 -- each timestamp is preceded with internet ID of the
registering entity
3 -- the internet ID fields are prespecified. An IP module only
registers its timestamp if it matches its own ID with the
next specified internet ID;
internet ID = ID for the timestamping device;
timestamp = a right-justified, 32-bit timestamp in milliseconds modulo 24 hours from midnight UT.
The timestamp option is not copied upon fragmentation. It is carried in