Start accepting longer prefixes as IPv4 depletes?

Wed Dec 8 22:12:37 UTC 2010

On Dec 8, 2010, at 12:01 PM, Cameron Byrne wrote:

> On Wed, Dec 8, 2010 at 11:41 AM, Dobbins, Roland <rdobbins at arbor.net> wrote:
>> 
>> On Dec 9, 2010, at 2:38 AM, Cameron Byrne wrote:
>> 
>>>  I still fail to see the value of LISP in a mature and sane  IPv6 world.
>> 
>> Abstraction of the global routing table away from direct dependence upon the underlying transport in use at a given endpoint network alone offers huge benefits for futureproofing; there are lots of other benefits as well, for mobility, CDNs, and so forth.
>> 
> 
> I believe a lot of folks think the routing paths should be tightly
> coupled with the physical topology.  If not, there is MPLS.
> 
LISP doesn't separate the routing paths from the physical topology.
It abstracts the end system identifiers so that they are not tied to the
physical topology.

> If underlying transport is IPv6, i don't see the incremental value
> (hence mature IPv6 world comment, most major ISPs are pretty well
> along the way).  IP Mobility as in Mobile IP already exists .... not
> terribly popular.
> 
It's barely had a chance to see even small deployments, so, judging
its popularity is extremely premature.

The value of LISP is the ability to have a strictly hierarchical routing
table with good aggregation where the Locator (routing field) in the
packet header is not directly tied to the Identifier (end-system
globally unique value).

IMHO, a more ideal way to do this would be to add 32 bits to the
packet header for "destination ASN" and do IDR based on that,
but, changing the packet header at this time is hard and would
require a new IP version number.

> There is already abstraction within most ISPs with MPLS.  Yet another
> layer of abstraction is just not something i would consider lightly
> with Internet scale.  Just my humble opinion.
> 
MPLS doesn't accomplish IDR abstraction which is the value here.

> Today, IPv6 provides real value with larger address space.  MPLS
> provides real value with FRR and network virtualization (MPLS L3
> VPNs).  In a mature IPv6 world, that is sane, i am not sure what the
> real value of LISP is.
> 
> But, IMHO, i do think there is something to the long term value of
> ILNP.  I am just very biased again additional tunnels,
> encapsulation/overhead, complexity, and that is what LISP is, edge to
> edge tunnels.  Then there is the question of who benefits from LISP
> and who pays.  The edge pays and the DFZ guys benefit (they deffer
> router upgrades).... i already pay the DFZ guys enough today.
> 
I agree that tunnels and encapsulation are not ideal. Hence my thinking
it would be better to rev. IP again and build the destination ASN into
the packet header with a defined value for "not yet known".

Owen