🚀 go-pugleaf

In article <18116@oolong.la.locus.com> bhk@merak.la.locus.com (Brad Kemp) writes:
>In article <CMM.0.88.655642509.jon@gode.ifi.uio.no> jon@ifi.uio.no (Jon Oelnes) writes:
>>In the ISO connection-less network protocol (ISO8473) one function is
>>Route Recording. I have only an old copy (DIS version) at hand, and my
>>question is if the following text is still valid, and if my interpretation
>>is correct:
>
> [ valid text Deleted ]
>
>>Now, reassembly is normally performed in the final _end system_, not in the
>>ISes. My interpretation of the text is that no restriction is posed on
>>reassembly in the _end systems_. An ES may perfectly well reassemble
>>fragments which have followed different routes.
>>Also, the point of discarding (in an IS) fragments which followed different
>>routes, is only valid if the IS really does reassembly. If it just passes
>>the fragments on, no error occures.
>
>Unfortunatly fragements which follow different routes and which have
>the Compelete Route Recording selected will never reach an ES.
>Lost fragements will also cause the PDU to never reach an ES.
>It is mandatory for IS's to be able to reaseemble.
>Although it is never mentioned in the standard, IS's should foward
>all PDU fragments through the same route if Complete Route Recording or
>Security is set. Both these functions require 
>the PDU to be dropped if the PDU cannot be reassembled.

These comments appear to imply some requirements on routers which
I was unaware of, and some of which I am not sure I understand.

The reference to security requiring that all packets follow the same
path does not match the goals of such proposed work as SP3, where
between two security routers, packets may follow whatever route they
find.  In addition, re-assembly at the end router is supported by
the fact that the router is intercepting these packets for local
processing anyway (under the most general SP3 encapsulation in fact the
packets are addressed to the remote security router).  I am therefore
not clear on what is meant by the reference above to security requiring
intermediate re-assembly and common paths.

With regard to complete route recording.  If the routers must perform
re-assembly, is it legitimate for the routers to decide instead to
always drop any fragmented packet which is requesting complete route
recording?  Re-assembling packets on the fly which are not intended
for local processing can be a real headache.

Thanks,
Joel M. Halpern			jmh@nsco.network.com
Network Systems Corporation

P.S. Does anyone know what the current ISPs/GOSIPs say about support
	for the compelte route recording option?