On 1/22/13 10:15 AM, Luigi Iannone wrote:
> Hi All,
>
> the definition of LSB as of the to-be-soon-rfc lisp specification is:
>
> LISP Locator Status Bits (LSBs):  When the L-bit is also set, the
>       locator status bits field in the LISP header is set by an ITR to
>       indicate to an ETR the up/down status of the Locators in the
>       source site. 
>
> I think that this clears Damien's question since LSB has no
> "reachability" meaning, rather it is a message from the site telling
> "from my perspective ETR X is up and running".
>
> (BTW this may help debugging, since if the ETR is running but not
> reachable from the outside this clearly shows that the problem is
> along the path somewhere. Yeah… could be a long path… but it is still
> useful information).
>
> The main concern is about security. Obviously LSB can be easily
> spoofed in a public environment and this is documented in section
> 6.4.1 of the draft-ietf-lisp-threats, which recommends:
>
>    Locator Status Bits can be blindly trusted only in secure
>    environments.  In the general unsecured Internet environment, the
>    safest practice for xTRs is to confirm the status change
>    through the mapping system.
>
>
> So IMHO the thing to do is to simply put a reference to the
> lisp-threats draft about the use of LSBs.
>

And actually I would recommend a small change to
draft-ietf-lisp-threats, changing 'through the mapping system' to
'through other means'.  Otherwise it is possible to introduce circular
dependencies.
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