(All) NHRP - Address Prefix Extension

["M.J. Robinson" <[e-mail]>]

Dimitry (and other ROLCers),

> As to your case I think you'd use R2R in the following way:
> 
>  When A wants to send trafic to a destination for which it doesn't have
>  a specific route, it sends a Request with a mask of all ones (or prefix
>  length of 32 as Yakov suggested). If this desination is reached via an exit
>  router E, E replies with the prefix length of the route to the desination.
>  Now A may use the shortcut to E to send traffic to all destinations covered
>  by the route that E provided.  Desitnations through F and G are resolved
>  in the same way.
> 
> I hope it helps.
> 
> Dimitry

	Thanks. This sounds like what I was imagining.

	I'm still concerned that the NHRP Responder can't always return
the "correct" Address Prefix length by itself - especially in the case of
an exit router (diagram available on request). Such concern is also raised
in NHRP I-D 06.
	A way in which this problem could be dealt with is to enforce the
progressive lengthening of an Address Prefix as the Request is forwarded
towards the Responder. For this to work properly though, everyone must
take part.
	Can anyone think of other ways to ensure the returned Address
Prefix length is correct ?
	How big a problem is this considered to be for "vanilla" NHRP ? 

	Matthew.