Leo,

On Mar 19, 2013, at 11:57 AM, Leo Bicknell <bickn...@ufp.org> wrote:
> In a message written on Tue, Mar 19, 2013 at 11:33:33AM -0700, David Conrad 
> wrote:
>> LISP doesn't replace BGP. It merely adds a layer of indirection so you don't 
>> have to propagate identity information along with routing topology, allowing 
>> much greater aggregation.
> The problem with LISP is that when the complexity of the entire
> system is taken into account it is not signficantly more efficient
> than the current system.  

When was the last time you (as a network operator) cared about the efficiency 
of the entire system?

LISP (and similar) system are inherently more complex because they're adding a 
new element to the network -- TANSTAAFL. The point is that the complexity is 
added at the edge where it is easy/cheap (per node or site). Yes, entire system 
complexity goes up.  However from the perspective of the core where life is 
fast/expensive, complexity goes down since identity is separated from location. 

> A LISP network is a similar model, with LISP nodes caching rather than 
> linecards.

You're comparing the equivalent of a DNS lookup with a FIB lookup.  Yes, there 
is a performance hit when you do the mapping of identity to location 
(TANSTAAFL), however this is at the edge in the millisecond DRAM-stored 
connection initiation world, not in the core in the nanosecond SRAM-stored 
packet forwarding world.

Regards,
-drc


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