[e2e] IP options over e2e path

Lynne Jolitz lynne at telemuse.net
Wed Mar 29 10:33:06 PST 2006

Since the RFC is very clear, the question becomes "why do they drop packets in contravention to the RFC instead of simply passing them through"?
Is it a business reason - one of anticompetitive tactics (I heard this from a businessman)?
Is it a deep technical reason, one of security, where, for example, such an ability allows one to pass out-of-band information which elides content filtering on firewalls?
Or is it simply that product development groups, given a set of product reqs, tested only against a certain set of IP packets for compliance, and dropped things that didn't matter (and yes, it does happen)?
In any case, the Red Queen's Race problem is magnified by this failure to comply with the RFC in the routers if new options are introduced.
Lynne Jolitz.

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> -----Original Message-----
> From: end2end-interest-bounces at postel.org
> [mailto:end2end-interest-bounces at postel.org]On Behalf Of Xiaoming Fu
> Sent: Wednesday, March 29, 2006 6:44 AM
> To: Mikael.Latvala at nokia.com
> Cc: end2end-interest at postel.org
> Subject: Re: [e2e] IP options over e2e path
> This is unfortunately (at least partially) happening: from measurements 
> done by ICIR/BBN colleagues, 
> http://www.icir.org/tbit/TCPevolution-Mar2005.pdf
> over 70% connection requests with an unknown IP option were lost,
> about 44% connections were broken if inserting the unknown IP option in 
> the middle of transfer.
> Xiaoming
> Mikael.Latvala at nokia.com wrote:
> > Hello,
> > 
> > The IP option provides a convinient way to add additional information to
> > the IP header. But what is the fate of an IP packet, which carries a
> > relatively new IP option inserted by a source host and which is not
> > recognized by most of the routers and/or middleboxes that the packet
> > traverses through?
> > 
> > RFC1812 says that "A router MUST ignore IP options which it does not
> > recognize."
> > 
> > However, some people I have talked to claim that such packets with a
> > relatively unknown IP option have no chance of reaching the final
> > destiny.
> > 
> > Is this really the case? Do new/unrecognized IP options prevent an IP
> > packet from reaching its final destination? Any research papers which
> > would back up or contradict this claim? Or perhaps this is yet another
> > undocumented NAT feature?
> > 
> > /Mikael

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