routing table go boom

Tue Mar 19 23:23:35 UTC 2013

David Conrad wrote:

> One of the advantages I see in LISP(-like) solutions is that it
> allows multi-homing without having to do BGP...

By having a lot larger table than BGP.

http://datatracker.ietf.org/doc/draft-ietf-lisp-architecture/?include_text=1

   It should be noted that the caching spoken of here is likely not
   classic caching, where there is a fixed/limited size cache, and
   entries have to be discarded to make room for newly needed entries.
   The economics of memory being what they are, there is no reason to
   discard mappings once they have been loaded (although of course
   implementations are free to chose to do so, if they wish to).

Worse, the table is updated so frequently.

http://datatracker.ietf.org/doc/draft-ietf-lisp-introduction/?include_text=1

   A node may have more than one
   RLOC, or its RLOC may change over time (e.g. if the node is mobile),
   but it keeps the same EID.

Assuming that there are 4G mobile devices in the world, the
mapping table has more than 4G entries each updated every
minute or second.

The problem of LISP is that it breaks the end to end principle
to introduce intelligent intermediate entities of ITR and ETR.

Mobility can best be handled end to end by end systems of MN,
HA and, optionally, CN.

						Masataka Ohta

PS

Considering that the Internet is connectionless because all the
routers have routing tables covering all the IP addresses in
realtime, LISP won't be operational unless most of routers
in DFZ have full mapping table in realtime.