On Mon, Mar 12, 2012 at 3:50 PM, Tim Chown <tjc@ecs.soton.ac.uk> wrote:
On 12 Mar 2012, at 19:30, Owen DeLong wrote:
I know my view is unpopular, but, I really would rather see PI made inexpensive and readily available than see NAT brought into the IPv6 mainstream. However, in my experience, very few residential customers make use of that 3G backup port.
So what assumptions do you think future IPv6-enabled homenets might make about the prefixes they receive or can use? Isn't having a PI per residential homenet rather unlikely?
Hi Tim, Not at all. You just build a second tier to the routing system. BGP is at the top tier. The second tier anchors SOHO users' provider independent addresses to a dynamically mapped set of top-tier relay addresses where each address in the relay anchor set can reach the SOHO's IP. Then you put an entry relay at many/most ISPs which receives the unrouted portions of PI space, looks up the exit relay set and relays the packet. The ingress relays have to keep some state but it's all discardable (can be re-looked up at any time). Also, they can be pushed close enough to the network edge that they aren't overwhelmed. The egress relays are stateless. Do it right and you get within a couple percent of the routing efficiency of BGP for SOHOs with only two or three ISPs. There are some issues with dead path detection which get thorny but they're solvable. There's also an origin filtering problem: packets originating from the PI space to BGP routed space aren't relayed and the ISP doesn't necessarily need to know that one of the PA addresses assigned to customer X is acting as an inbound relay for PI space. Again: solvable. If you want to dig in to how such a thing might work, read: http://bill.herrin.us/network/trrp.html Regards, Bill Herrin -- William D. Herrin ................ herrin@dirtside.com bill@herrin.us 3005 Crane Dr. ...................... Web: <http://bill.herrin.us/> Falls Church, VA 22042-3004