Re: [RRG] Comments on draft-lewis-lisp-interworking

["William Herrin" <bill@herrin.us>]

On Mon, Mar 24, 2008 at 8:04 PM, Brian E Carpenter
<brian.e.carpenter@gmail.com> wrote:
>  Maybe I'm naive, but I'd been assuming that EIDs would in practice be
>  identically equal to addresses allocated under a registry-allocated
>  PI prefix.  So the provider can know about the prefix just like today,
>  even if there's no advertisement. I don't see why that would change
>  fundamentally, even if the proposed LISP-ALT EID prefix space is used.

Hi Brian,

We don't want to trade consumption in the routing table for
consumption in the source filter; they both consume the FIB. If your
transit provider is filtering your source addresses like he's supposed
to, he'll have to carry a filter for every distinct block of EIDs
downstream. In practice this means that he'll find it too much trouble
to carry any source filters and we'll have a fresh problem with
spoofed source addresses. The problem isn't especially tractable with
BGP but it looks worse under map-enacap.

Regards,
Bill Herrin

-- 
William D. Herrin ................ herrin@dirtside.com  bill@herrin.us
3005 Crane Dr ....................... Web: <http://bill.herrin.us/>
Falls Church, VA 22042-3004

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