Subject: Re: [lisp] Comments on draft-fuller-lisp-alt-04

From: [email-masked] (Noel Chiappa)
Date: Fri, 6 Feb 2009 17:46:22 -0500 (EST)

> From: Scott Brim <[email-masked]>

    >> (Also, of course, this information is being propogated not as paths
    >> _to the ETR_, but paths _to the chunk of address space_

    > Nit: not to a chunk of address space, but to one or more mapping
    > authorities for a chunk of address space.

Now I'm confused. I thought that if ETR P (with EID Ep and RLOC Rp) were
responsible for a chunk of namespace x.y.0.0/z, the thing that would be
propogated up the ALT hierarchy (as advertisements, not in response to a Map
Request) was a route to x.y.0.0/z, _not_ to Ep or Rp.

That's what I meant to encompass with my comment about "[what] is [actually]
being propogated [is] not .. paths _to the ETR_, but paths _to the chunk of
[name] space_".

Yes, in some high-level sense it's paths to mapping authorities, but... their
'names' which are being propogated through the ALT are not the names of the
mapping authorities _themselves_ (i.e. Ep or Rp), but the name(s) of the
_chunk of namespace they are authoritative for_ (i.e. x.y.0.0/z).

"I trust I make myself obscure?" (T. More, in MfaS...)

	Noel

---

From: Scott Brim <[email-masked]>
Date: Fri, 6 Feb 2009 23:00:30 -0500

> Request) was a route to x.y.0.0/z, _not_ to Ep or Rp.

The protocol on the wire is the same but what does it _mean_?  In base
BGP if you see an announcement of "1.1.0.0/16" it means "I can forward
data packets addressed to something in 1.1.0.0/16 with reasonable
confidence that they will get there".  In ALT BGP it means "I can
forward Map-Requests for EIDs in 1.1.0.0/16 to someone who will tell
you how to forward data packets there".  

> That's what I meant to encompass with my comment about "[what] is
> [actually] being propogated [is] not .. paths _to the ETR_, but
> paths _to the chunk of [name] space_".
> 
> Yes, in some high-level sense it's paths to mapping authorities,
> but... their 'names' which are being propogated through the ALT are
> not the names of the mapping authorities _themselves_ (i.e. Ep or
> Rp), but the name(s) of the _chunk of namespace they are
> authoritative for_ (i.e. x.y.0.0/z).
> 

Very clear.  Right, the mapping authorities' names are not being
propagated since they don't aggregate.  Very clever of ALT, eh?

Scott