Hi Dino,
Sorry to be slow, but this is one of those cases where a complete expansion
might be called for:
1) On the public Internet, we shouldn't trust the LSB at all. If an ITR detects
any transition (0-to-1 or 1-to-0), verify it with the mapping system.
2) In a controlled Environment, we can trust the LSB
2a) If the ITR detects a transition from 1-to-0, we should believe it. There is
no need to verify. In fact, if we did check with the mapping system, we might
find that the mapping system still reports the bit as 1. This is because, as
you say below, LSB "are good in control[ed] environments to take ETRs out of
service without having to update the mapping database."
2b) If the ITR detects a transition from 0-to-1, we should believe it. There is
no need to verify. But if we did verify, it would be more likely that the
mapping system would report the same thing.
Also, in the bullet points above, I am not quite sure what the definition of a
"controlled environment" is. Am I correct in assuming that an environment is
"controlled" if it satisfies both of the following requirements:
-controlled from a security perspective. Bad guys cannot spoof LISP control
information on the data plane.
-controlled from a routing perspective. ETRs are aware of each others' status
(and, therefore, can report on each others' status) because the participate in
a common IGP.
Ron
> -----Original Message-----
> From: Dino Farinacci [mailto:[email protected]]
> Sent: Monday, January 21, 2013 10:15 PM
> To: Ronald Bonica
> Cc: Noel Chiappa; [email protected]; [email protected]; lisp-
> [email protected]
> Subject: Re: [lisp] Should we use Locator-Status-Bits in Internet
> deployment?
>
> They have the same meaning in all environment. It is a question when
> they should be verified. An LSB that changes in a public environment
> can cause a Map-Request to be sent and a signed Map-Reply can verify
> the LSB in an authenticated matter.
>
> Dino
>
> On Jan 21, 2013, at 6:05 PM, Ronald Bonica <[email protected]> wrote:
>
> > Dino,
> >
> > But isn't it troubling that the bits have one meaning in a controlled
> environment and another in the great-wide Internet?
> >
> > Ron
> >
> >
> >> -----Original Message-----
> >> From: [email protected] [mailto:[email protected]] On Behalf
> >> Of Dino Farinacci
> >> Sent: Monday, January 21, 2013 5:51 PM
> >> To: Noel Chiappa
> >> Cc: [email protected]; [email protected]; lisp-
> >> [email protected]
> >> Subject: Re: [lisp] Should we use Locator-Status-Bits in Internet
> >> deployment?
> >>
> >>> (I don't remember off the top of my head why I didn't like them: I
> >>> think it was a combination of the fixed number of bits, the fact
> >>> that it might be difficult for ETR X to know the state of ETR Y,
> the
> >>> fact that 'reachable from ITR A' [which you _really_ need to have
> >>> anyway] is a subset of 'up', etc, etc. But we didn't desperately
> >>> need the header bits, and the mechanism wasn't positively harmful,
> >>> so I didn't bother to put up a big fight over it... :-)
> >>
> >> Maybe because they could be spoofed?
> >>
> >> But they are good in control environments to take ETRs out of
> service
> >> without having to update the mapping database.
> >>
> >> Dino
> >>
> >>
> >> _______________________________________________
> >> lisp mailing list
> >> [email protected]
> >> https://www.ietf.org/mailman/listinfo/lisp
> >
> >
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