What's really needed is a routing slot market (was: Using IPv6 withprefixes shorter than a /64 on a LAN)

William Herrin bill at herrin.us
Mon Feb 7 10:30:05 CST 2011


On Mon, Feb 7, 2011 at 9:25 AM, Jamie Bowden <jamie at photon.com> wrote:
> It would help if we weren't shipping the routing equivalent of the pre
> DNS /etc/hosts all over the network (it's automated, but it's still the
> equivalent).  There has to be a better way to handle routing information
> than what's currently being done.

Hi Jamie,

Consensus in the routing research arena is that it's a layer boundary
problem. Layer 4/5 (TCP, various UDP-based protocols) intrudes to
deeply into layer 3. Sessions are statically bound at creation to the
layer 3 address. Unlike the dynamic MAC to IP bindings (with ARP) the
TCP to IP bindings can't change during the potentially long-lived
session. Thus route proliferation is needed to maintain them.

Much better routing protocols are possible, but you first either have
to break layer 3 in half (with a dynamic binding between the two
halves that renders the lower half inaccessible to layer 4) or you
have to redesign TCP with dynamic bindings to the layer 3 address.
Ideas like LISP take the former approach. Ideas like SCTP and
Multipath TCP take the latter. The deployment prospects are not
promising.

Modest improvements like FIB compression are in the pipeline for DFZ
routing, but don't expect any earth shattering improvements.

Regards,
Bill Herrin


-- 
William D. Herrin ................ herrin at dirtside.com  bill at herrin.us
3005 Crane Dr. ...................... Web: <http://bill.herrin.us/>
Falls Church, VA 22042-3004




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