[Rsvp] RE: doubt

[Bob Lindell]

> hi bob!
> 
> sometimes it would be good if a error message (such as a path error) is only
> send to an intermediate host. you might remember the security discussion
> where a path message hits a node (the path msg contains an integrity object)
> but unfortunately the path changed and the cryptographic verification fails.
> hence the path message is returned to the data sender which is of no help. 

Why is the path message "returned"?  A packet that fails cryptographic
authentication is dropped.  Why should an implementation assume that
a message with an incorrect digest contains a valid message type (e.g.
a PATH message)?

> 
> example:
> 
>       /-------> b
> a ----  
>       \-------> c
> 
> router a forwards a path message and includes an integrity object. he
> assumes that the message is send to router b. unfortunately it is send to
> router c (because of a route change). imagine there is an entire network
> between a and b/c. 
> 
> hence cryptopgraphic verification fails at router c. he transmits a path
> error message back to the data source. this verification failure is only a
> problem between the participating routers. Ideally, router a would recognize
> this path change and would add a new integrity object with the security
> association shared with router c. 

All potential receivers should be configured to share a security
association with a sender LIH.  Non-RSVP clouds can make this
configuration more complex than would be desired.  Such is life.


Bob Lindell

> 
> ciao
> hannes
> 
> 
> > -----Original Message-----
> > From: owner-rsvp@ISI.EDU [mailto:owner-rsvp@ISI.EDU]On Behalf Of Bob
> > Braden
> > Sent: Tuesday, September 17, 2002 12:01 AM
> > To: rsvp@ISI.EDU; hemanth_khare@rediffmail.com
> > Cc: schultz@io.iol.unh.edu
> > Subject: Re: doubt
> > 
> > 
> >   *>    After reading this section what i have in mind is 
> > that error in 
> >   *> the PERR message will be reported to the sender (data source).
> >   *> 
> >   *>    But the error may be caused by the intermediate 
> > nodes. In that 
> >   *> case error must be reported intermediate node and not to sender 
> >   *> application (data source).
> >   *> 
> > 
> > What good would it do to notify intermediate nodes, when the
> > error is caused by erroneous data from the sender RSVP?
> > Only the sender is in a position to correct the error.
> > 
> > Bob Braden
> > 
> >   *>    Please let me know ur thoughts on this aspect.
> >   *> 
> >   *> TIA and Regards,
> >   *> -hemanth
> >   *> __________________________________________________________
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