Subject: Re: [rrg] [lisp] Economic issues of long-path / stretched routing

From: [email-masked] (Noel Chiappa)
Date: Mon, 26 Jan 2009 14:03:07 -0500 (EST)

> From: [email-masked]

    > Why LISP 1.5=20?  Why not LISP 2 ? or directly:
    > Why doesn't the ITR intercept and enhance the DNS lookup as to also request
    > the eRLOC address in addition to the dest IP address? It can also
    > intercept the respective response and store (EID, eRLOC).

I don't know what the thinking of other people working on LISP is, but I can
give you my thoughts on this point.

Simply put, I don't like designs which _invisibly, outside the host_ tie into
the DNS because it takes two separate subsystems (DNS resolution, and basic
packet forwarding), and tangles them together, which is bad engineering for a
number of reasons (makes it harder to make further changes, creates more
mutual dependencies, increases overall fragility/brittleness, etc).

Some NAT variants do this too, and I especially didn't like them either! :-)

        Noel
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From: Luigi Iannone <[email-masked]>
Date: Tue, 27 Jan 2009 10:11:43 +0100

>     > intercept the respective response and store (EID, eRLOC).
Besides the reasons the Noel gave, which I agree on, using DNS generates
more issues than solutions IMHO.

Not all DNS queries go through an ITR, since probably there will be a
DNS cache inside the domain.
Using DNS in this case means that synchronization between DNS caches and
LISP caches is needed!
This is already difficult IMO, and it is even worse if you think that
DNS cache has been designed for a totally different purpose, which I do
not think fits in the requirements of the LISP cache.

Luigi