On Feb 7, 2011, at 8:30 AM, William Herrin wrote: > On Mon, Feb 7, 2011 at 9:25 AM, Jamie Bowden <ja...@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
