Dick St.Peters says:
Quoted from RFC791, the IP specification, in the section on loose
source routing, page 19 [emphasis added]:
If the address in destination address field has been reached and
the pointer is not greater than the length, the next address in
the source route replaces the address in the destination address
field, and the recorded route address REPLACES THE SOURCE
ADDRESS just used, and pointer is increased by four.
...
An end-to-end-inviolate source address is not a required part of the
IP spec.
If you look upward two paragraphs from the part you quoted, you'll
see that "source address" does not mean the first address in the
fixed part of the IP header, but the address in the "route data"
provided by the source.
______________________________________________________________________________
Matt Crawford crawdad(_at_)fnal(_dot_)gov
Fermilab
"A5.1.5.2.7.1. Remove all classified and CCI boards from the COMSEC equipment,
thoroughly smash them with a hammer or an ax, and scatter the pieces."