Hi Mark, Thanks for the long reply; I found it very interesting. A few more comments in-line..
(hopefully this won't drift too far off-topic..) On 7 Aug 2003, Mark Smith wrote: > On Thu, 2003-08-07 at 17:47, Pekka Savola wrote: > > On Thu, 7 Aug 2003, Andrew White wrote: > > > > Just responding to a few points.. > > > > > > Real example: My ISP's DSL connection decides to drop the connection and > > > reconnect (with a new IPv4 address, and thus 6to4 prefix) every 1-3 hours. > > > I'd rather not subject my internal network to that if I don't have to. > > > > Switch ISP or complain to them. I certainly wouldn't bear with that kind > > of behaviour. > > > > If that kind of ISP techniques are commonplace, we may need to do > > something. But I'm not sure if that's the case. Experiences? > [...] > Since the realisation that dial-up was a dying technology, a lot of the > dial up ISPs are providing ADSL, wholesaling it from Telstra. According > to this page (http://www.broadbandchoice.com.au/isp-list.cfm), there are > currently 149 residential ISPs in Australia, which is probably quite a > lot for a country with only 20 million or so people. Ok, that's a lot: how many of these is typically available in a geographical area? That is, when you live in city X, how many possible ISP's are there? That is, do the ISPs have any incentive to be competitive about the customers? I.e. if one ISP provided static addresses "for free" (or something) but still the regular bandwith caps, would that possibly spark some interest for people to change to that model (and in turn, perhaps encourage the other ISPs to also change their IP assignment model..) > A typical residential ADSL service is : > > * Single IPv4 address, so you have to use NAT if you want more than one > machine (although at least one enlightened ISP allows up to 8 PPP(oE|oA) > logins at once on a single ADSL service) This is no problem in itself (IMO).. [...] > * The single IPv4 address can change over time. Most ISPs don't specify > the time period, and it varies, but I expect that having the same single > IPv4 address for a week is starting to be an an exception, rather than a > rule. .. but this might be. Do all (or most) of the ISPs changing the address also provide "premium" static IP service? I assume your home PC (based on your description) is always on, so that these changes are not causes by e.g. reboots or DHCP lease expirations? [snip a lot of interesting detail] > A lot of these ISPs also want to provide business ADSL over the same > wholesaled ADSL infrastructure. They typically do this by : > > * Guaranteeing a single IPv4 address, that won't change. > > * Optionally routing a prefix for the customer LAN ie. no NAT. > > A lot of small business customers probably don't take this up, probably > because they are told about the "security" using NAT. I'd suspect in > most cases not having to change internal IPv4 addressing is not even a > "NAT or not" consideration. Is it significantly more costly to obtain e.g. the static IPv4 address as a premium service? For homes? > > Note: consider how many of these techniques are used to prevent people > > from keeping servers at their home systems (i.e., does the ISP consider > > the changing address a bug or feature). > > Certainly a feature. > > ISPs quickly learnt not to filter incoming TCP / UDP ports to prevent > people running "servers", http or otherwise, so they use the reliability > of the single IPv4 address they allocate as a dis-incentive to running a > "server". One might be able to make up a few legimate reasons for unnecessarily changing IP addresses, but I think the real reason is possibly the business case, and developing IPv6 might not actually help the situation that much.. > > Also consider how the situation > > would change (if any) with IPv6 provided by the ISP. > > > > I'd suspect they would probably allocate periodically changing /128s to > their residential ADSL users. Let's hope not. > > Real example: at home, I use DHCP on DSL to get addresses. During 1 year, > > the addresses have changed _once_ (the ISP changed the prefix from which > > it allocated the DSL users' addresses). That's good enough for me, and I > > even manually glue all the IPv4 and resulting 6to4 addresses in my > > configuration files, filters etc. > > So what is the weather like in Finland ? I might consider moving :-) At the moment it's nice, but Winters here are _real_, not like there Down Under... :-) -- Pekka Savola "You each name yourselves king, yet the Netcore Oy kingdom bleeds." Systems. Networks. Security. -- George R.R. Martin: A Clash of Kings -------------------------------------------------------------------- IETF IPng Working Group Mailing List IPng Home Page: http://playground.sun.com/ipng FTP archive: ftp://playground.sun.com/pub/ipng Direct all administrative requests to [EMAIL PROTECTED] --------------------------------------------------------------------
