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From: brescia@PARK-STREET.BBN.COM (Mike Brescia)
Newsgroups: comp.protocols.tcp-ip
Subject: Re: Question about IP options
Message-ID: <8709101329.AA01481@ucbvax.Berkeley.EDU>
Date: Thu, 10-Sep-87 09:30:12 EDT
Article-I.D.: ucbvax.8709101329.AA01481
Posted: Thu Sep 10 09:30:12 1987
Date-Received: Sat, 12-Sep-87 07:34:44 EDT
References: <8709092342.AA03527@PHOEBE.CAM.UNISYS.COM>
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    ... not clearly answered in either RFC 791 or MIL-SPEC 1777:

     1)  Are the record route and timestamp options modified by the source and
         destination systems, or are they only modified by gateways?

A clear recommendation that hosts implement them would help.  You could make
use of the information provided by the source host such as 'which interface
was used to actually send the packet', and the destination host 'what time was
the packet received'.

     2)  When using either loose or strict source routing, does the next hop
         or the final destination go in the destination address field of the
         IP header?

Next hop.  A rationale for this choice, based on processing power needed, is
that a gateway does not have to look at the options unless the IP destination
address is the gateway.  Then you look for options, and, finding a source
route, send it back out again.

     3)  Is it legal to have both loose and strict source routing options in the
         same IP packet?  If so, how do you handle this case?

Legal?  Since it's not forbidden, I guess so.  What path would a host program
expect such a packet to trace?  How more useful is it than just one option?
Think what the gateway must do if both are present; process the first? do the
second if the first is counted out?  do the first and ignore the second?