The subset of tree topology where a consumer places ones router behind another router is *extremely* common. Statistics I saw several years ago suggested that probably about 60% of ADSL customers in the US use this topology. The most common cause for this topology is where the service provider supplies a free ADSL router with a single port to a subscriber, and the subscriber then puts their own multi-port router behind that router. The ADSL router is configured to do the PPPoE, and is also configured to automatically provide whatever public IP address it gets to whatever is behind it (via DHCPv4, as a sort of automatic DMZ function -- the ADSL router also uses that public IP address for its needs). The ADSL router is often set to provide only that one address, and not to support a full network of devices. Which is why consumers are forced to use their own router. This also tends to be how VoIP router + consumer's wireless router topology works.
I'm sure some people would like to argue as to why this is bad, or it shouldn't be done. I'm not going to get into that argument. That argument is irrelevant. The fact is that it's very, very common. I agree with those who say that we *don't* need to make sure IPv4 works everywhere that IPv6 works. But I think it's an absolute requirement that IPv6 MUST work everywhere that IPv4 works. And this is a very common case where IPv4 works. When going to IPv6, the ADSL router will also be the device that establishes the IPv6 connection. Because the credentials are the same as for IPv4, and the secondary router doesn't have those credentials. And the consumer forgot the credentials long ago, and doesn't remember how to configure this stuff anyway. IMO, I believe that the best approach would be to solve tree generically. Which means that the probability of "tree network" would actually be "common, perhaps 30th percentile" (dividing my "60% in ADSL networks" by 2). Barbara > -----Original Message----- > On 10/7/11 12:48 AM, Fred Baker wrote: > > I suggested that the probability of use of each of the scenarios on > slide 4 were > > single router network: 90th percentile > > tree network: unusual > > multi-router: perhaps 5th percentile > > multihomed: unusual > > Fred, > > are the above numbers based on any survey data? > > Reason I'm asking is that I have two consumer devices with IPv4 NAT in > my home (a VoIP box and a backup device) where the instructions said: > 1. Insert between or existing router (or PC if you have no router) and > the DSL/cable modem > 2. Insert between your PC and your existing router (or modem if you > have > no router) > > Those consumer instructions naturally result in a daisy-chain of IPv4 > RGs/NATs, which is a subset of a tree topology. > > I can't be the only person who have a VoIP box or a Time Capsule. > > Erik > _______________________________________________ > homenet mailing list > [email protected] > https://www.ietf.org/mailman/listinfo/homenet _______________________________________________ homenet mailing list [email protected] https://www.ietf.org/mailman/listinfo/homenet
