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

Mon Feb 7 20:04:06 UTC 2011

On Feb 7, 2011, at 8:30 AM, William Herrin wrote:

> 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.
> 
On the other hand, when we can deprecate global routing of IPv4, we
will see an earth shattering improvement as the current 10:1 prefix
to provider ratio (300,000 prefixes for ~30,000 active ASNs) drops
to something more like 2:1 in IPv6 due to providers not having to
constantly run back to the RIR for additional slow-start allocations.

Owen