in defense of lisp (was: Anybody can participate in the IETF)

Wed Jul 13 15:22:33 UTC 2011

On Jul 13, 2011, at 10:39 AM, Scott Brim wrote:

> On Wed, Jul 13, 2011 at 10:09, Randy Bush <randy at psg.com> wrote:
>> btw, a litte birdie told me to take another look at
>> 
>> 6296 IPv6-to-IPv6 Network Prefix Translation. M. Wasserman, F. Baker.
>>     June 2011. (Format: TXT=73700 bytes) (Status: EXPERIMENTAL)
>> 
>> which also could be considered to be in the loc/id space
>> 
>> randy
> 
> No, that's a misuse of "loc/id" since no identification is involved,
> even at the network layer -- but it is in the "reduce issues in global
> routing and local renumbering" space (that's part of what LISP does).

interesting, because that is exactly what Mike O'Dell suggested it as - a prefix/identification (loc/id) split. If you're going to take your line of reasoning, ILNP doesn't provide an identifier (as the term is defined in RFC 1992), and neither does LISP except as it redefines the terms to make it do. You're looking for something along the lines of HIP - which has other problems.

I would describe NPTv6 as a location/identifier split in the sense that it makes the endpoint identifier in the IPv6 address independent of ISP's prefix - the PA (and therefore aggregatable) prefixes used outside the edge network are translated to the prefix used within the shop, and the host doesn't have to mess with them. As you point out, PA prefixes help with the route table - we aren't carrying infinite numbers of PI prefixes.

To my way of thinking, shim6 was DOA if anything because it transferred the complexity of managing the route table from the transit networks to the edge networks, and the edge networks lacked both the expertise and the desire to deal with it. Folks are trampling the RIRs to get PI prefixes to avoid the multi-prefix model. But making the route table aggregate requires PA prefixes. Deploying ILNP (which is in many ways superior) requires a change to the TCP/UDP pseudoheader. Deploying NPTv6 makes the edge network look PA to the transit network, PI to the edge network, and doesn't change TCP. There is a headache with http/sip/etc referrals, which are better served if they use domain names anyway. But to my mind referrals have a solution if people choose to use it, so it's a solvable problem. So to me, NPTv6 fits pretty nicely.