Subject: [lisp] Interworking - NAT

From: "Joel M. Halpern" <[email-masked]>
Date: Wed, 25 Mar 2009 12:52:35 -0400

Reading the interworking NAT description, I am trying to figure out 
which one of two cases it is trying to address.

For context, as I read it, LISP-NAT attempts to do 1-1 NAT in the 
address space for IPv4.

One case is some time in the future when significant parts of the world 
are (hypothetically) on LISP.  In that case, the number of hosts needing 
to talk to non-LISP palces at any given time may well be small.  Getting 
a sufficient pool of aggregatable addresses for such communication 
without affecting other parts of the IPv4 world may be doable.

In contrast, if folks could get 1-1 NAT for IPv4 now then that would be 
a viable solution to a number of real world problems already.  We as a 
community are looking are recommending something similar as part of IPv6 
(NAT66).  If that could be done for v4 in the current world, I am not at 
all clear on why a site would bother with the rest of LISP.  Given 
typical site attitudes, that sort of NAT would seem sufficient for them.

Yours,
Joel M. Halpern

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From: David Meyer <[email-masked]>
Date: Wed, 25 Mar 2009 10:20:41 -0700

> For context, as I read it, LISP-NAT attempts to do 1-1 NAT in the  

	If you mean 1-1 NAT from the IPv4 EID space to the IPv4 RLOC
	space, yes.

> typical site attitudes, that sort of NAT would seem sufficient for them.

	Perhaps, however, 1-1 NAT still carries a lot of
	operational burden for sites deploying the
	technology. Deploying PTR infrastructure eases this
	burden, and provides quite a bit of additional
	functionality. I think of it as a tool in the toolkit
	that can be useful in some cases.

	Dave

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From: Dino Farinacci <[email-masked]>
Date: Wed, 25 Mar 2009 18:30:43 -0700

>> n contrast, if folks could get 1-1 NAT for IPv4 now then that would  
>> be

Also NAT cannot describe TE policy and has issues with asymmetric  
paths in and out of a site.

Dino

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From: David Meyer <[email-masked]>
Date: Thu, 26 Mar 2009 09:26:18 -0700

On Wed, Mar 25, 2009 at 06:30:43PM -0700, Dino Farinacci wrote:
> Also NAT cannot describe TE policy and has issues with asymmetric paths 
> in and out of a site.

Yep, agreed.

Dave