Subject: Re: [lisp] ETR connectivity to site - question on EID reachability (section 6.4)

From: [email-masked] (Noel Chiappa)
Date: Wed, 25 May 2011 13:10:56 -0400 (EDT)

> From: Darrel Lewis <[email-masked]>

    >> Whether a LISP box is a PE router or a CPE router should not matter
    >> when it comes to how it responds to a particular situation, should it? 

    > a presentation discussing the trade-offs between CPE and PE xTRs
    > ... One of the obvious differences is the fact that the xTRs are not
    > under the administrative control of the site when the xTR is a PE. 

Oh, I understand that from an O+M viewpoint, the PE/CPE difference can be
big (huge, even), and O+M issues can have a big influence over where one
places various LISP functional elements.

When I said the above, what I meant was 'if a LISP box is a LISP functional
element of type X (be it ETR, ITR, MR, MS, etc, etc), its response to a given
situation (erroneous data, etc, etc) should really only depend on how that
kind of LISP element is supposed to respond to that situation, not things like
which entity controls it administratively'.

So, from that point of view, is there in fact a way in which a LISP box
which is a PE router or a CPE router should respond differently, when it
comes to responding to a particular situation (e.g. lost control packet,
box failure, topology change, etc, etc, etc)?

I looked through the presentation, but didn't see anything that suggested
such. The only thing I can possibly think of is places where a LISP box
notices something that potentially requires human intervention: administrative
issues might cause it to respond differently (e.g. if it's a home box, it
probably isn't much use telling the owner, the homeowner, since most won't
have the ability to do anything useful with the information).

	Noel

---

From: Darrel Lewis <[email-masked]>
Date: Wed, 25 May 2011 12:35:12 -0700

> have the ability to do anything useful with the information).

The presentations mention a lack of egress TE control from the site is one technical issue, but I'm not sure if you consider that O&M.  Basically what if the site (which only has 2 defaults upward) send packets to one PE, that after encap, would have been best sent to the other PE...

The lack of central administrative control makes things like LSB synchronization hard, which I think is technical.

-Darrel